DOI: 10.1002/chem.201303735
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& Heterometallic Complexes
Structural and Photophysical Study on Heterobimetallic Complexes with d8–d10 Interactions Supported by Carborane Ligands: Theoretical Analysis of the Emissive Behaviour Olga Crespo,*[a] M. Concepcin Gimeno,*[a] Antonio Laguna,[a] Olli Lehtonen,[b] Isaura Ospino,[a] Pekka Pyykkç,[b] and M. Dolores Villacampa[a] In memory of Mara Pilar Garca Clemente
Abstract: Heterobimetallic complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] (M = Pd, Pt; M’ = Au, Ag, Cu) and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] were obtained from the reaction of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (M = Pd, Pt) with [M’(PPh3)] + (M’ = Au, Ag, Cu) or by one-pot synthesis from [(SH)2C2B10H10], (PPh2)2C2B10H10, NiCl2·6 H2O, and [Au(PPh3)] + . They display d8–d10 intermetallic interac-
Introduction New structural patterns that are expected to be luminescent can be proposed on the basis of studies on the emissive properties of known coordination complexes. We call such patterns structural emissive origins (SEO). Combining several SEOs in the same compound could lead to tuneable emissions upon small structural changes. Some examples of SEOs are: 1) Metal–thiolate bonds, which lead in many cases to ligand (thiolate)-to-metal charge-transfer (LMCT) transitions that can cause emissions which stretch over the green-red region in gold complexes;[1] 2) Metal–fluorophore bonds, because the intrinsic fluorophore emissions may be modified upon coordination to the metal. In this work, we were especially interested in the nido bis-phosphane[2] [7,8(PPh2)2C2B9H10] as fluorophore; 3) Metal–metal interactions, which may be responsible for emissions that involve the electron density between the metal centres. Such emissions may originate from metal-centred (MC) transitions or from chargetransfer transitions [ligand-to-metal–metal (LMMCT) or metal– metal-to-ligand (MMLCT)].[3]
[a] Dr. O. Crespo, Prof. M. C. Gimeno, Prof. A. Laguna, Dr. I. Ospino, Dr. M. D. Villacampa Departamento de Qumica Inorgnica, Universidad de Zaragoza-CSIC Instituto de Sntesis Qumica y Catlisis Homognea (ISQCH) Pedro Cerbuna 12, 50009 Zaragoza (Spain) Fax: (+ 34) 976761187 E-mail: [email protected] [email protected] [b] Dr. O. Lehtonen, Prof. P. Pyykkç Department of Chemistry, University of Helsinki P.O.B 55 (A. I. Virtasen aukio 1), 00014 Helsinki (Finland) Chem. Eur. J. 2014, 20, 3120 – 3127
tions and emit red light in the solid state at 77 K. Theoretical studies on [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M = Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)-to“P2-M-S2” (ML’) charge-transfer (LML’CT) transitions for M = Pt and to metal (M)-to-“P2-M-S2” (ML’) charge-transfer (MML’CT) transitions for M = Ni, Pd.
We have now combined these three SEOs in heterobimetallic complexes. The rigidity and steric demand of the carborane skeleton allowed us to synthesise a group of complexes that display d8–d10 metal–metal interactions: [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] [M = Pd, Pt; M’ = Au, Ag, Cu] and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)]. Figure 1 shows an exam-
Figure 1. Possible origins of the luminescence observed in the analysed system and the regions in which the emissions are frequently observed. In all three situations, M may be involved in the transitions, as the intraligand (bis-phosphane) transitions may be modified upon coordination to the metal atom.
ple of such structural motifs, which have scarcely been reported in the literature. About 25 structures in which a metal M (Ni, Pd, Pt) is coordinated by a dithiolate and two phosphorus atoms of a bis- or mono-phosphane in square-planar geometry and one or both sulfur centres form bridges to another metal 3120
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Full Paper planar complexes [M{(PPh2)2C2B10H10}(S2C2B10H10)] [M = Pd (3), M = Pt (4)]. The 31P{1H} NMR spectrum of complexes 3 and 4 display one signal at 68.6 (3) and 59.1 (4) ppm, which are shifted by about 10 and 3 ppm to higher and lower field, respectively, relative to those of the precursors [MCl2{(PPh2)2C2B10H10}]. Reaction of complexes 3 and 4 with [M’X(PPh3)n] (n = 1: M’ = Au, X = Cl; M’ = Ag, X = OTf. n = 2: M’ = Cu, X = NO3) in refluxing ethanol led to partial degradation of the carborane cage of the bis-phosphane ligand and coordination of the M’(PPh3) fragment to afford complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] [M = Pd, Pt; M’ = Au, Ag, Cu] (Scheme 1).
Figure 2. Structural types of published crystal structures showing the structural motif represented in Figure 1.
M’ (Cu, Ag, Au) were found in the CCDC.[4] The published structural types are summarised in Figure 2. Three points are notable: 1) About 15 of them show M(d8, Group 10)–M’(d10, Group 11) interactions, about nine of which are Pt–Ag interactions. 2) The structural types shown in Figure 2 are tri-, tetraor hexanuclear, with the sole exception of dinuclear complex 2 c. 3) The emissive behaviour of these complexes is almost unexplored. Different origins have been proposed for the luminescence observed for complexes 2 a and 2 b, in which diimine ligands complete the M(d10) coordination sphere, depending on the compound type and M(d10). Although the assignments of such emissions are not based on theoretical studies, the proposed origins of the luminescence include neither metal-centred (MC) transitions nor metal–metal interactions.[4a]
Results and Discussion Synthesis and characterization The reaction of (PPh2)2C2B10H10 with [MCl2(NCPh)2] (M = Pd, Pt) affords complexes [MCl2{(PPh2)2C2B10H10}] [M = Pd (1), M = Pt (2)]. The synthesis of both complexes has been previously described. By changing the solvent[5] from toluene or benzene to dichloromethane, we have shortened the reaction times. Both complexes react with the dithiol (SH)2C2B10H10 to afford squareChem. Eur. J. 2014, 20, 3120 – 3127
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Scheme 1. i) [MCl2(NCPh)2] (M = Pd, Pt); ii) K2CO3, (SH)2C2B10H10 ; iii) [AuCl(PPh3)], [Ag(OTf)(PPh3)], or [Cu(NO3)(PPh3)2]; iv) M = Ni, M’ = Au; (SH)2C2B10H10, [AuCl(PPh3)]; v) NiCl2·6 H2O, (SH)2C2B10H10, [AuCl(PPh3)].
These complexes contain a closo-carborane dithiolate and a nido-carborane bis-phosphane ligand and exhibit MAu (5, 6), MAg (7, 8) or MCu (9, 10) interactions. For complexes 3– 10 the n(BH) band is observed at about 2500 cm1. A multiplet at about 2 ppm due to the bridging hydrogen atom in the open face of the carborane resulting from the partial degradation process appears in the 1H NMR spectra of complexes 5– 10. Comparison of the integral of this signal with that of the broad resonance in the aromatic region indicated that only one carborane cage has been partially degraded. Nucleophilic attack is expected to occur on the carborane cluster of the bisphosphane ligand, rather than on that of the dithiolate. We confirmed this by X-ray studies (see below). The phosphorus atoms of the bis-phosphane appear as singlets in the 31P NMR spectra of complexes 5–10 at about 85 (M = Pd: 5, 7, and 9) or 65 ppm (M = Pt: 6, 8, and 10). These resonances are shifted to lower field relative to the starting material [M{(PPh2)2C2B10H10)}(S2C2B10H10)]. The chemical shift of the PPh3 ligand depends on M’: about 35 ppm for M’ = Au, about 15 ppm for M’ = Ag and 4 ppm (M = Pd: 9) or 4 ppm (M = Pt: 10) for M’ = Cu. Complexes 7 and 8 display one singlet and two doublets in their 31P{1H} NMR spectra. The singlet corresponds to the bis-phosphane, and the two doublets are as-
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Full Paper signed to coupling of the P atoms of the PPh3 ligand to the Crystal structure determinations silver isotopes 109Ag and 107Ag. With the aim of obtaining analogous complexes displaying The structures of complexes 5–7, 9, and 11 were determined NiM’ (M’ = Au, Ag, Cu) interactions, we carried out the reacby X-ray crystallography (Figure 3). They confirmed partial degtion of [NiCl2{(PPh2)2C2B10H10}] with (SH)2C2B10H10. It led to a mixradation of the carborane cage of the bis-phosphane ligand, ture of complexes which included the expected product, but and all of them show d8–d10 metallophilic interactions[6] partial degradation of the bis-phosphane was observed. As it (Table 1). The only crystal structures reported of heterometallic was not possible to obtain pure samples of [Nicomplexes with carborane ligands containing Group 11 and {(PPh2)2C2B10H10}(S2C2B10H10)], we tried a one-pot synthesis to obtain complexes with NiM’ (M’ = Au, Ag, Cu) interactions. Table 1. Bond lengths [] for [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)]. The reaction of NiCl2·6 H2O with Bond Compound (M/M’) (PPh2)2C2B10H10, (SH)2C2B10H10, 5 (Pd/Au) 6 (Pt/Au) 7 (Pd/Ag) 9 (Pd/Cu) 11 (Ni/Au) and [AuCl(PPh3)] in refluxing [a] 2.2592(12), 2.2689(18), 2.2517(11), 2.2527(13), 2.1700(12), MP methanol gave the expected 2.2851(12) 2.2417(18) 2.2600(11) 2.2569(13) 2.2023(13) product 11. The one-pot reacMS 2.3349(11), 2.3331(19), 2.3846(13), 2.4027(13), 2.1894(12), tion of [NiCl2{(PPh2)2C2B10H10}] 2.3905(12) 2.3629(18) 2.4035(11) 2.4172(13) 2.2296(12) 2.2599(12) 2.242(2) 2.3577(11) 2.1903(14) 2.2659(12) M’P[b] with (SH)2C2B10H10 and [AuClM’S 2.3282(11) 2.3338(12) 2.4918(10), 2.3172(13), 2.3488(11) (PPh3)] in refluxing methanol/ 2.8336(13) 2.4187(15) ethyl acetate gave similar yields. MM’ 3.2618(12) 3.2251(7) 2.9498(8) 2.7519(9) 3.0206(8) The 31P{1H} NMR spectrum of 11 0.00609 0.0885 0.0311 0.0060 0.0746 M[c] a[d] 93.8 86.5 76.9 104.1 84.5 displays one resonance at 74.5 ppm, due to the phospho[a] Phosphorus atoms of the bis-phosphane. [b] Phosphorus atom of PPh3. [c] Deviation of M from the plane built from P2, S1, S2. [d] Angle between planes 1 and 2: plane 1, built from atoms P1, P2, S1, and S2; plane 2, rus atoms of the bis-phosphane built from atoms: M’, P3, and S. P1 and P2: phosphorus atoms of the bis-phosphane; P3: phosphorous atom of and another at 34 ppm, correPPh3. sponding to the PPh3 ligand.
Figure 3. Molecular diagrams of complexes 5 (a), 6 (b), 7 (c), 9 (d), and 11 (e) showing the atom-labelling schemes. Hydrogen atoms have been omitted for clarity. Ellipsoids represent 50 % probability levels. Chem. Eur. J. 2014, 20, 3120 – 3127
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Full Paper Group 10 metal atoms are metallacarborane complexes[7] and the species [AgNiCl2{(PPh2)2C2B10H10}{(PPh2)2C2B9H10}],[8] in which both bis-phosphanes are coordinated in a chelating mode. The nido bis-phosphane is coordinated to the silver centre and the closo bis-phosphane to the Ni atom. No metal–metal interaction was reported for any of them. The PtAu distance in 6 resembles the shortest PtAu intermetallic interactions in the complexes discussed in the introduction,[4] whereas the PdCu and PdAg distances in 7 and 9 are shorter than those reported for such complexes. The M(d8) metal centres have a square-planar coordination environment. The main distortion is due to the bite angles of the chelating bis-phosphane and dithiolate ligands (Table 2).
Table 2. Bond angles [8] for complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)]. Compound (M/M’)
P[a]-M-P[a]
S-M-S
S-M’-P[b]
5 (Pd/Au) 6 (Pt/Au) 7 (Pd/Ag) 9 (Pd/Cu) 11 (Ni/Au)
82.75(4) 83.82(7) 85.57(4) 85.47(5) 84.79(5)
90.75(4) 91.03(6) 87.73(4) 84.92(5) 95.41(5)
175.44(3) 176.67(7) 156.24(4), 126.96(4) 141.41(5), 131.82(5) 176.27(5)
[a] Phosphorus atoms of the bis-phosphane. [b] Phosphorus atom of PPh3.
The S-M(d8)-S angles range between 95.41 and 84.928, and the P(bis-phosphane)-M(d8)-P(bis-phosphane) angles between 85.55 and 82.758 (Table 2). The M(d10) centres in 5, 6, and 11 are coordinated to the phosphorus atom of the PPh3 ligand and one of the sulfur atoms of the dithiolate in a distorted linear coordination mode. This distortion probably arises mainly from the M(d8) M(d10) metallophilic interaction (see Tables 1 and 2). For compound 7 a short distance of the silver atom to the other sulfur atoms of the dithiolate and a larger distortion from the linear geometry are observed compared to those of complexes 5, 6, and 11. In complex 9 the copper centre is coordinated to both sulfur atoms of the dithiolate, and the geometry of the copper centre can be described as highly distorted trigonal planar.
Figure 4. DRUV spectra of [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)].
Table 3. DRUV maxima, steady-state luminescence data, and lifetimes for complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] (5–11) in the solid state at 77 K. DRUV [nm]
lEm[a](lEx)[b] [nm]
t[c] [ms]
5 (Pd/Au) 6 (Pt/Au) 11 (Ni/Au) 7 (Pd/Ag) 8 (Pt/Ag) 9 (Pd/Cu) 10 (Pt/Cu)
310, 420 279, 365 320, 400, 500 305, 400 300, 415 267, 324 300, 400
630 620 600 615 610 650 600
39.7 43.1 55.6 96.6 26.9 61.2 83.4
(420) (400) (420) (420) (420) (380) (400)
[a] lEm = emission maximum. [b] lEx = excitation maximum. [c] Data were fitted to a first-order exponential decay (R2 = 0.97–0.99).
Photophysical studies The diffuse-reflectance (DR) UV spectra of complexes 5, 7, 8, and 10 exhibit similar patterns. They show a broad band with maxima between 267 and 320 nm and a shoulder with a maximum between 324 and 420 nm (Figure 4, Table 3). Complex 11 displays another shoulder at about 500 nm, which spreads to 610 nm. The spectra of complexes 6 and 9 follow the same pattern, but are shifted to higher energies. The most intense band appears at about 270 nm, and the shoulder at 324 nm. The bands at higher energies may be attributed to the phosphane aryl substituents, whereas that at lower energies may be due to metallophilic interactions or to charge-transfer transitions, which could involve the metal centres (d8 and/or d10) and the ligands (bis-phosphane and/or dithiolate). Chem. Eur. J. 2014, 20, 3120 – 3127
Complex (M/M’)
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The mononuclear complexes 1–4 are non-luminescent. Complexes 5–11 are not emissive in the solid state at room temperature. At 77 K they display emissions in the red region (620 nm) upon excitation at about 400 nm (Table 3). The lifetimes, in the microsecond range, and the Stokes shifts indicate a phosphorescent nature of the emission. The emission spectra display similar profiles for all complexes, although for compound 11 a structured band which spreads to 800 nm is observed (Figure 5). The analysis of the data in Table 3 suggests that the emission is not dependent on the metallophilic d8–d10 interaction. Thus, we propose that charge-transfer transitions are responsible for the luminescence. With the aim of elucidat-
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Figure 5. Emission spectra of [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)].
ing which ligand (dithiolate and/or bis-phosphane) and which metal centre (d8 and/or d10) are involved in such transitions, calculations were carried out in order to visualise the orbitals and make a proposal of how the transitions take place. Theoretical studies Complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (5, 6, and 11) were selected for a computational analysis. For all of the complexes, the crystallographic structures were used as models. The electronic structures of the complexes were obtained by single-point DFT calculations on model systems built up from the X-ray structures with the aim of analysing the frontier molecular orbitals involved in the electronic transitions responsible for the phosphorescence. Figure 6 shows a selection of the frontier orbitals. The HOMO2 for 5 and 6 and HOMO for 11 have thiolate and metal (d8) contributions. Electron delocalisation on the carborane cage was found for the HOMO of 5 and 6 and HOMO2 of 11. A predominant contribution of s-antibonding orbitals of the d8 metal centre and the dithiolate and bis-phosphane ligands in the LUMO orbitals is observed for the three complexes. An important point is that the metallophilic d8–d10 interaction does not make a relevant contribution to the frontier orbitals. This is in agreement with the emissive behaviour observed for the complexes, which does not seem to be dependent on the substitution of the d8 or d10 metal centre. Since the lifetimes and Stokes shifts point to a phosphorescent nature of Chem. Eur. J. 2014, 20, 3120 – 3127
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Figure 6. Selection of frontier molecular orbitals in [M{(PPh2)2C2B9H10}{S2C2B10H10}Au(PPh3)].
the emissions, the TDDFT method was employed to analyse the first singlet!triplet transitions for complexes 5, 6, and 11 and the molecular orbitals involved in such transitions. By comparing the calculated vertical excitation and experimental excitation wavelengths, we can propose that such a transition is responsible for the luminescence. Table 4 lists the more important orbitals involved in this transition. We note that the calculated singlet!triplet excitation energies are lower than the corresponding experimental values. Calculations at this qualitative level do not allow any definitive conclusion about MO energy levels, and the relation between excitation energy and differences in MO energies is only approximately correct. From the data of Table 4 and Figure 6 we can attribute the origin of the luminescence to a charge-transfer transition from
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Table 4. Calculated vertical excitation (lT) and experimental excitation (lEx) energies for complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)]. Compound (M/M’)
lEx [nm/eV]
lT [nm/eV]
Transition
5 (Pd/Au) 6 (Pt/Au) 11 (Ni/Au)
420/2.95 400/3.10 420/2.95
587/2.10 490/2.52 571/1.42
HOMO1(269)!LUMO(271) HOMO(270)!LUMO(271) HOMO1(269)!LUMO(271)
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Full Paper the ligand (L, nido-carborane) to the metal–ligand group “S2M(d8)-P2” (ML’) (LML’CT transition) for complex 6 (M = Pt), and for complexes 5 (M = Pd) and 11 (M = Ni) to charge transfer from the metal [M(d8)] to the metal–ligand group “S2-M(d8)-P2” (ML’) (MML’CT charge transfer). The different origins of the emissive behaviour could be related to the different electronic character of the d8 metal centre, as Pt has the more stable d orbitals.
Conclusion A new family of red emitters of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] [M = Pd, Pt; M’ = Au, Ag, Cu] and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] has been synthesised. The complexes exhibit a fluorophore ligand (nido-carborane bis-phosphane), a dithiolate (which may be responsible for metal-to-thiolate or thiolate-to-metal charge-transfer transitions) and d8 M(Ni, Pd, Pt)–d10 M’(Cu, Ag, Au) interactions, which also may lead to emissive behaviour. Calculations for [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M = Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)-to-“P2-M(d8)-S2” group (ML’) charge-transfer (LML’CT) transitions for M = Pt and to metal [M(d8)]-to-“P2-M(d8)-S2” group (ML’) charge-transfer (MML’CT) transitions for M = Ni, Pd.
Experimental Section General comments (SH)2C2B10H10,[9] (PPh2)2C2B10H10,[10] [MCl2{(PPh2)2C2B10H10}] [M = Pd,[5a] Pt,[5b] Ni[11]], [AuCl(PPh3)],[12] [Ag(OTf)(PPh3)],[13] and [Cu(NO3)(PPh3)2][14] were synthesised according to published procedures. Other reagents and solvents were used as received. Solution 1H and 31P NMR spectra were recorded with Bruker Avance 400 and Bruker DPX 300 spectrometers. If not specified, the 400 MHz spectrometer was used. The chemical shifts were referenced to residual resonances of protiated solvent and external 85 % H3PO4 in the 1H and 31P spectra, respectively. Mass spectra were determined on a Bruker APEX-Qe ESI FT-ICR instrument in the ESI + mode. DRUV spectra were recorded on Unicam UV-4 spectrophotometer equipped with a Spectralon RSA-UC-40 Labsphere integrating sphere. The solid samples were mixed with dried KBr to obtain a homogeneous powder. The mixtures were placed in a homemade cell equipped with quartz window. The intensities are given in Kubelka–Munk units. Steady-state photoluminescence spectra were recorded on a HORIBA Jobin Yvon Fluorolog FL-3-11 spectrometer with band pathways of 3 nm for both excitation and emission. Phosphorescence lifetimes were recorded with a Fluoromax phosphorimeter accessory containing an UV xenon flash tube.
Synthesis [PdCl2{(PPh2)2C2B10H10}][M=Pd (1), M = Pt (2)]: [MCl2(NCPh)2] (0.1 mmol, M = Pd: 38.4 mg, M = Pt: 47.2 mg) was added to a solution of (PPh2)2C2B10H10 (0.1 mmol, 50.9 mg) in dichloromethane (20 mL). The solution was stirred for 2 (M = Pd) or 6 h (M = Pt). Concentration of the solution under reduced pressure and addition of n-hexane led to precipitation of 1 and 2 as yellow solids in 98 and 87 % yield, respectively. Data for 1: elemental analysis calcd (%) for C26H30B10Cl2P2Pd: C 45.26, H 4.38; found: C 44.96, H 4.25; 1H NMR (CDCl3, ppm): d = 1–3 (br m, 10 H, BH), 7.54–7.58 (br m, 8 H, Ph), Chem. Eur. J. 2014, 20, 3120 – 3127
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7.63–7.72 (br m, 4 H, Ph), 8.21–8.27 (br m, 8 H, Ph); 31P{1H} NMR (CDCl3, ppm): 79.0 (s); IR (cm1): n˜ (BH) = 2560 (s). Data for 2: elemental analysis calcd (%) for C26H30B10Cl2P2Pt: C 40.10, H 3.88; found: C 39.76, H 3.49; 1H NMR (CDCl3, ppm): d = 1–3 (br m, 10 H, BH), 7.56–7.64 (br m, 8 H, Ph), 7.72–7.82 (br m, 8 H, Ph), 8.23–8.28 (br m, 4 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 56.4 (s, J(195Pt,P) = 1876.0 Hz); IR: n˜ (BH) = 2566 cm1 (s). [M{(PPh2)2C2B10H10}(S2C2B10H10)] [M = Pd (3), M = Pt (4)]: An excess of K2CO3 was added to a solution of (SH)2C2B9H10 (0.1 mmol, 20.8 mg) in dichloromethane (20 mL). The resulting suspension was stirred for one hour, and [MCl2{(PPh2)2C2B10H10}] (0.1 mmol, M = Pd: 68.6 mg, M = Pt: 77.6 mg) was added. The mixture was stirred for 3.0 h (M = Pd) or 6.0 h (M = Pt) and filtered through Celite. The resulting solution was concentrated to about 5 mL. Addition of nhexane led to the precipitation of 3 and 4 as pale yellow solids in 78 and 74 % yield, respectively. Data for 3: elemental analysis calcd (%) for C28H40B20P2PdS2 : C 40.74, H 4.88, S 7.77; found: C 41.03, H, 4.98, S 7.70; 1H NMR (CDCl3, ppm): d = 0–3.5 (br m, 20 H, BH), 7.52– 7.55 (br m, 8 H, Ph), 7.60–7.64 (br m, 4 H, Ph), 8.05–8.10 (br m, 8 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 68.6 (s); IR (cm1): n˜ (BH) = 2568 (s). Data for 4: elemental analysis calcd (%) for C28H40B20P2PtS2 : C 36.79, H 4.41, S 7.01; found: C 36.16, H 3.91, S 6.87; 1H NMR (CDCl3, ppm): 0–3 (br m, 20 H, BH), 7.59–7.75 (br vm, 15 H, Ph), 8.05–8.10 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): 59.1 (s, J(195Pt,P) = 1469.2 Hz); IR (cm1): n˜ (BH) = 2561 (s). [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] [M = Pd (5), Pt (6)]: [AuCl(PPh3)] (0.1 mmol, 49.7 mg) was added to a solution of [M{(PPh2)2C2B10H10}{S2C2B10H10}] (0.10 mmol, M = Pd: 78.9 mg, M = Pt: 91.0 mg) in ethanol (20 mL). The mixture was heated to reflux for 2 h (M = Pd) or 3 h (M = Pt). The solids that precipitated were collected by filtration and washed with n-hexane to give 5 (yellow, 81 % yield) and 6 (pale yellow, 62 % yield). Data for 5: elemental analysis calcd (%) for C46H55AuB19P3PdS2 : C 43.37, H 4.35, S 5.03; found: C 43.09, H 4.00, S 4.75; 1H NMR (CDCl3, ppm): d = 2.19 (br s, 1 H, B-H-B), 0–3 (br m, 19 H, BH), 6.99–7.03 (br m, 5 H, Ph), 7.29–7.42 (br m, 10 H, Ph), 7.64–7.78 (br m, 15 H, Ph), 8.02–8.05 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 80.3 (s, bis-phosphane), 34.4 (s, PPh3); IR (cm1): n˜ (BH) = 2560 (s). Data for 6: elemental analysis calcd (%) for C46H55AuB19P3PtS2 : C 40.55, H 4.06, S 4.70; found: C 40.95, H 4.53, S 4.06; 1H NMR (CDCl3, ppm): d = 2.30 (br s, 1 H, B-H-B), 0–3.5 (br m, 19 H, BH), 7.01–7.03 (br m, 5 H, Ph), 7.35–7.72 (br vm, 25 H, Ph), 7.94–7.98 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): 60.1 (s, J(P,195Pt) = 1528.4 Hz, bis-phosphane), 32.7 (s, PPh3); IR (cm1): n˜ (BH) = 2555 (s). [M{(PPh2)2C2B9H10}(S2C2B10H10)Ag(PPh3)] [M = Pd (7), Pt (8)]: [Ag(OTf)(PPh3)] (0.1 mmol, 51.8 mg) was added to a solution of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (0.10 mmol, M = Pd: 78.9 mg; Pt: 91.0 mg) in ethanol (20 mL) . The mixture was heated to reflux for 2 h (M = Pd) or 5 h (M = Pt). During this period a yellow solid precipitated, which was filtered off and washed with n-hexane to give 7 (78 % yield) and 8 (56 % yield). Data for 7: elemental analysis calcd (%) for C46H55AgB19P3PdS2 : C 46.63, H 4.67, S 5.41; found: C 46.82, H 4.78, S 5.10; 1H NMR (CDCl3, ppm): d = 2.08 (br s, 1 H, BH-B), 0–3 (br m, 19 H, BH), 6.91–6.94 (br m, 5 H, Ph), 7.27–7.44 (br m, 10 H, Ph), 7.60–7.69 (br m, 15 H, Ph), 8.06–8.11 (br m, 5 H, Ph); 31P{1H} NMR (300 MHz, CDCl3, ppm): d = 84.4 (s, bis-phosphane), 15.01 (td, J(109Ag,P) = 692.55, J(107Ag,P) = 595.34 Hz, PPh3); IR (cm1): n˜ (BH) = 2568 (s). Data for 8: elemental analysis calcd (%) for C46H55AgB19P3PtS2 : C 43.38, H 4.35, S 5.03; found: C 43.94, H 4.63, S 4.70; 1H NMR (CDCl3, ppm): 2.20 (br s, 1 H, B-H-B), 0–3.5 (br m,
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Full Paper 19 H, BH), 6.94–6.97 (br m, 5 H, Ph), 7.29–7.39 (br m, 10 H, Ph), 7.55– 7.67 (br m, 15 H, Ph), 7.96–8.0 (br m, 5 H, Ph); 31P{1H} NMR (300 MHz, CDCl3, ppm): 62.5 (s J(195Pt,P) = 1515.6 Hz, bis-phosphane), 12.7 (dd, J(109Ag,P) = 716.85, J(107Ag,P) = 615.04 Hz, PPh3); IR (cm1): n˜ (BH) = 2562 (s). [M{(PPh2)2C2B9H10}(S2C2B10H10)Cu(PPh3)] [M = Pd (9), Pt (10)]: A suspension of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (0.10 mmol, M = Pd: 78.9 mg, M = Pt: 91.0 mg) and [Cu(NO3)(PPh3)2] (0.10 mmol, 64.9 mg) in ethanol (20 mL) was heated to reflux for 2 h (M = Pd) or 3 h (M = Pt). The solid that precipitated was filtered off and washed with n-hexane to give 9 (yellow, 77 % yield) or 10 (pale yellow, 52 % yield). Data for 9: elemental analysis calcd (%) for C46H55CuB19S2P3Pd: C 48.44, H 4.86, S 5.62; found: C 48.14, H 4.53, S 5.86; 1H NMR (CDCl3, ppm): d = 2.05 (br s, 1 H, B-H-B), 0–3.5 (br m, 19 H, BH); 6.86–6.78 (br m, 5 H, Ph); 7.38–7.66 (br vm, 25 H, Ph), 8.05–8.10 (br m, 5 H, Ph), 31P{1H} NMR (CDCl3, ppm): d = 87.3 (s, bis-phosphane), 3.9 (s, PPh3); IR (cm1): n˜ (BH) = 2560 (s). Data for 10: elemental analysis calcd (%) for C46H55CuB19P3PtS2 : C 44.95, H 4.51, S 5.21; found: C 44.68, H,4.27, S 5.36; 1 H NMR (CDCl3, ppm): d = 2.15 (br s,1 H, B-H-B), 0–3.5 (br m, 19 H, BH), 7.06–7.20 (br m, 10 H, Ph), 7.29–7.75 (br vm, 20 H, Ph), 7.99–8.05 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): 62.5 (s, J(195Pt,P) = 1521.5 Hz, bis-phosphane), 3.3 (s, PPh3); IR (cm1): n˜ (BH) = 2578 (s).
Crystallography A crystal of each compound was mounted in inert oil on a glass fibre and transferred to the cold gas stream of a Xcalibur Oxford Diffraction diffractometer (5, 6, 7, 9, and 11) or Bruker Smart Apex CCD (6) equipped with a low-temperature attachment. Data were collected by using monochromated MoKa radiation (l = 0.71073 )
Table 5. X-ray data for complexes 5–7.
formula crystal system space group a [] b [] c [] a [8] b [8] g [8] V [3]/Z 1calcd [Mg m3] m [mm1] F(000) T [8C] 2 qmax measured reflns independent reflns transmission Rint parameters restraints wR(F2, all reflns) R [I > 2s(I)] S D1max [e 3]
[Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (11): Method a: (SH)2C2B10H10 (0.1 mmol 20.8 mg) and [AuCl(PPh3)] (0.1 mmol 49.7 mg) were added to a solution of [NiCl2{(PPh2)2C2B10H10}] (0.10 mmol, 77.3 mg) in methanol (20 mL). The solution was heated to reflux for 4 h. During this time a red solid appeared which was filtered off and washed with n-hexane (60 % yield). Method b: A solution of (PPh2)2C2B10H10 (0.10 mmol, 50.9 mg) and NiCl2·6 H2O (0.10 mmol, 23.7 g) in ethyl acetate/methanol (10/10 mL) was stirred for 10 min, after which (SH)2C2B10H10 (0.1 mmol, 20.8 mg) and [AuCl(PPh3)] (0.1 mmol, 49.7 mg) were added. The solution was heated to reflux for 4 h. During this time a red solid appeared which was filtered off and washed with n-hexane (90 % yield). Elemental analysis calcd (%) for C46H55AuB19NiP3S2 : C 46.27, H 4.64, S 2.68; found: C 46.94, H 4.95, S 2.47; 1H NMR (CDCl3, ppm): d = 2.44 (br s,1 H, B-H-B), 0–3.5 (br m, 19 H, BH); 6.99–7.03 (br m, 5 H, Ph); 7.19–7.23 (br m, 5 H, Ph), 7.33– 7.38 (br m, 5 H, Ph), 7.60–7.74 (br m, 15 H, Ph), 8.04–8.08 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 74.5 (s, bis-phosphane); 34.6 (s, PPh3); IR (cm1): n˜ (BH) = 2568 (s).
DFT and TDDFT calculations In all calculations the PBE functional[15] and TURBOMOLE 6.0 program[15c, 16] were used. Single-point DFT[17] calculations were performed on model systems built up from the X-ray structures. The calculated vertical excitation energies were obtained by the timedependent (TD) DFT approach.[18] The Karlsruhe split-valence quality def2-SV(P) basis sets with additional polarization functions on non-hydrogen atoms were used.[19] The resolution of the identity method was used to speed up calculations.[20] The Stuttgart effective core potentials, which include scalar relativistic effects, were used for Ni, Pd, Pt, and Au.[21] The calculations were performed without symmetry constraints. Chem. Eur. J. 2014, 20, 3120 – 3127
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5
6
7
C46H54AuB19P3PdS2 triclinic P1 11.432(2) 15.421(3) 16.144(3) 82.08(3) 84.36(3) 75.12(3) 2718.6(9)/2 1.555 3.225 1254 173 50 10 0882 9546 0.626–0.734 0.0494 653 21 0.0692 0.0288 1.058 1.219
C49H60AuB19P3PtS2 triclinic P 1 11.575(3) 13.389(3) 19.235(5) 78.242(5) 85.205(4) 78.588(5) 2857.8(12)/2 1.631 5.201 1366 173 50 22 149 9988 0.530–0.746 0.0581 734 18 0.0947 0.0431 0.984 1.449
C48H57AgB19Cl6P3PdS2 triclinic P1 12.184(2) 15.788(3) 17.317(4) 72.28(3) 85.81(3) 89.75(3) 3164.1(11)/2 1.494 1.024 1424 173 50 90 662 11110 0.923–0.960 0.0246 807 21 0.0891 0.0376 0.0827 1.599
Table 6. X-ray data for complexes 9 and 11. Compound
9
11
formula crystal system space group a [] b [] c [] a [8] b [8] g [8] V [3]/Z 1calcd [Mg m3] m [mm1] F(000) T [8C] 2 qmax measured reflns independent reflns transmission Rint parameters restraints wR(F2, all reflns) R [I > 2s(I)] S D1max [e 3]
C48H57B19Cl6Cu P3PdS2 triclinic P1
C46H55AuB19NiP3S2 monoclinic P21/n 10.948(2) 28.848(6) 17.306(4) 90 90.53(3) 90 5465.5(19)/4 1.490 3.224 2440 173 50 58 474 8480 0.374–0.627 0.0776 729 0 0.0648 0.0354 0.980 1.473
12.103(2) 15.632(3) 17.342(4) 106.74(3) 93.14(3) 90.95(3) 3135.2(11)/2 1.461 1.060 1388 173 50 88 498 11 008 0.857–0.949 0.0458 801 21 0.1295 0.0545 0.916 2.383
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Full Paper with scan type w. Absorption correction based on multiple scans was applied with the program SADABS.[22] The structure was refined on F2 by using the program SHELXL-97.[23] All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included by using a riding model. Further details of the data collection and refinement are given in Tables 5 and 6. CCDC 961295 (5), 961296 (6), 961297 (7), 961298 (9), and 961299 (11) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements We thank the Ministerio de Economa y Competitividad for project MEC/FEDER CTQ2007-67273-C02-01 and grant BES2008002858 and the Academy of Finland for project 126905. We also thank the Finnish Centre of Excellence in Computational Molecular Science (CMS) and the CSC-IT Centre for Science, Espoo, Finland, for the computer resources provided. Keywords: carboranes · heterometallic complexes luminescence · metal–metal interactions · transition metals
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[1] E. R. T. Tiekink, J.-G. Kang, Coord. Chem. Rev. 2009, 253, 1627and references therein. [2] a) O. Crespo, M. C. Gimeno, P. G. Jones, A. J. M. Lpez-de-Luzuriaga, M. Monge, J. L. Prez, M. A. Ramn, Inorg. Chem. 2003, 42, 2061; b) R. Czerwieniec, T. Hofbeck, O. Crespo, A. Laguna, M. C. Gimeno, H. Yersin, Inorg. Chem. 2010, 49, 3764. [3] Z.-N. Chen, N. Zhao, F. Yang, J. Ni, Coord. Chem. Rev. 2009, 253, 1; and references therein. [4] a) Y.-D. Chen, Y.-H. Qin, L.-Y. Zhang, L.-X. Shi, Z.-N. Chen, Inorg. Chem. 2004, 43, 1197; b) S. D. Robertson, A. M. Z. Slawin, J. D. Woollins, Eur. J. Inorg. Chem. 2007, 247; c) Y.-D. Chen, L.-Y. Zhang, L.-X. Shi, Z.-N. Chen, Inorg. Chem. 2004, 43, 7493; d) Y.-H. Qin, M.-M. Wu, Z.-N. Chen, Chin. J. Struct. Chem. 2005, 24, 621; e) J. Vicente, M. T. Chicote, S. Huertas, P. G. Jones, A. K. Fischer, Inorg. Chem. 2001, 40, 6193; f) J. Vicente, M. T. Chic-
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Received: September 24, 2013 Published online on February 13, 2014
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& Heterometallic Complexes
Structural and Photophysical Study on Heterobimetallic Complexes with d8–d10 Interactions Supported by Carborane Ligands: Theoretical Analysis of the Emissive Behaviour Olga Crespo,*[a] M. Concepcin Gimeno,*[a] Antonio Laguna,[a] Olli Lehtonen,[b] Isaura Ospino,[a] Pekka Pyykkç,[b] and M. Dolores Villacampa[a] In memory of Mara Pilar Garca Clemente
Abstract: Heterobimetallic complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] (M = Pd, Pt; M’ = Au, Ag, Cu) and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] were obtained from the reaction of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (M = Pd, Pt) with [M’(PPh3)] + (M’ = Au, Ag, Cu) or by one-pot synthesis from [(SH)2C2B10H10], (PPh2)2C2B10H10, NiCl2·6 H2O, and [Au(PPh3)] + . They display d8–d10 intermetallic interac-
Introduction New structural patterns that are expected to be luminescent can be proposed on the basis of studies on the emissive properties of known coordination complexes. We call such patterns structural emissive origins (SEO). Combining several SEOs in the same compound could lead to tuneable emissions upon small structural changes. Some examples of SEOs are: 1) Metal–thiolate bonds, which lead in many cases to ligand (thiolate)-to-metal charge-transfer (LMCT) transitions that can cause emissions which stretch over the green-red region in gold complexes;[1] 2) Metal–fluorophore bonds, because the intrinsic fluorophore emissions may be modified upon coordination to the metal. In this work, we were especially interested in the nido bis-phosphane[2] [7,8(PPh2)2C2B9H10] as fluorophore; 3) Metal–metal interactions, which may be responsible for emissions that involve the electron density between the metal centres. Such emissions may originate from metal-centred (MC) transitions or from chargetransfer transitions [ligand-to-metal–metal (LMMCT) or metal– metal-to-ligand (MMLCT)].[3]
[a] Dr. O. Crespo, Prof. M. C. Gimeno, Prof. A. Laguna, Dr. I. Ospino, Dr. M. D. Villacampa Departamento de Qumica Inorgnica, Universidad de Zaragoza-CSIC Instituto de Sntesis Qumica y Catlisis Homognea (ISQCH) Pedro Cerbuna 12, 50009 Zaragoza (Spain) Fax: (+ 34) 976761187 E-mail: [email protected] [email protected] [b] Dr. O. Lehtonen, Prof. P. Pyykkç Department of Chemistry, University of Helsinki P.O.B 55 (A. I. Virtasen aukio 1), 00014 Helsinki (Finland) Chem. Eur. J. 2014, 20, 3120 – 3127
tions and emit red light in the solid state at 77 K. Theoretical studies on [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M = Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)-to“P2-M-S2” (ML’) charge-transfer (LML’CT) transitions for M = Pt and to metal (M)-to-“P2-M-S2” (ML’) charge-transfer (MML’CT) transitions for M = Ni, Pd.
We have now combined these three SEOs in heterobimetallic complexes. The rigidity and steric demand of the carborane skeleton allowed us to synthesise a group of complexes that display d8–d10 metal–metal interactions: [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] [M = Pd, Pt; M’ = Au, Ag, Cu] and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)]. Figure 1 shows an exam-
Figure 1. Possible origins of the luminescence observed in the analysed system and the regions in which the emissions are frequently observed. In all three situations, M may be involved in the transitions, as the intraligand (bis-phosphane) transitions may be modified upon coordination to the metal atom.
ple of such structural motifs, which have scarcely been reported in the literature. About 25 structures in which a metal M (Ni, Pd, Pt) is coordinated by a dithiolate and two phosphorus atoms of a bis- or mono-phosphane in square-planar geometry and one or both sulfur centres form bridges to another metal 3120
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Full Paper planar complexes [M{(PPh2)2C2B10H10}(S2C2B10H10)] [M = Pd (3), M = Pt (4)]. The 31P{1H} NMR spectrum of complexes 3 and 4 display one signal at 68.6 (3) and 59.1 (4) ppm, which are shifted by about 10 and 3 ppm to higher and lower field, respectively, relative to those of the precursors [MCl2{(PPh2)2C2B10H10}]. Reaction of complexes 3 and 4 with [M’X(PPh3)n] (n = 1: M’ = Au, X = Cl; M’ = Ag, X = OTf. n = 2: M’ = Cu, X = NO3) in refluxing ethanol led to partial degradation of the carborane cage of the bis-phosphane ligand and coordination of the M’(PPh3) fragment to afford complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] [M = Pd, Pt; M’ = Au, Ag, Cu] (Scheme 1).
Figure 2. Structural types of published crystal structures showing the structural motif represented in Figure 1.
M’ (Cu, Ag, Au) were found in the CCDC.[4] The published structural types are summarised in Figure 2. Three points are notable: 1) About 15 of them show M(d8, Group 10)–M’(d10, Group 11) interactions, about nine of which are Pt–Ag interactions. 2) The structural types shown in Figure 2 are tri-, tetraor hexanuclear, with the sole exception of dinuclear complex 2 c. 3) The emissive behaviour of these complexes is almost unexplored. Different origins have been proposed for the luminescence observed for complexes 2 a and 2 b, in which diimine ligands complete the M(d10) coordination sphere, depending on the compound type and M(d10). Although the assignments of such emissions are not based on theoretical studies, the proposed origins of the luminescence include neither metal-centred (MC) transitions nor metal–metal interactions.[4a]
Results and Discussion Synthesis and characterization The reaction of (PPh2)2C2B10H10 with [MCl2(NCPh)2] (M = Pd, Pt) affords complexes [MCl2{(PPh2)2C2B10H10}] [M = Pd (1), M = Pt (2)]. The synthesis of both complexes has been previously described. By changing the solvent[5] from toluene or benzene to dichloromethane, we have shortened the reaction times. Both complexes react with the dithiol (SH)2C2B10H10 to afford squareChem. Eur. J. 2014, 20, 3120 – 3127
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Scheme 1. i) [MCl2(NCPh)2] (M = Pd, Pt); ii) K2CO3, (SH)2C2B10H10 ; iii) [AuCl(PPh3)], [Ag(OTf)(PPh3)], or [Cu(NO3)(PPh3)2]; iv) M = Ni, M’ = Au; (SH)2C2B10H10, [AuCl(PPh3)]; v) NiCl2·6 H2O, (SH)2C2B10H10, [AuCl(PPh3)].
These complexes contain a closo-carborane dithiolate and a nido-carborane bis-phosphane ligand and exhibit MAu (5, 6), MAg (7, 8) or MCu (9, 10) interactions. For complexes 3– 10 the n(BH) band is observed at about 2500 cm1. A multiplet at about 2 ppm due to the bridging hydrogen atom in the open face of the carborane resulting from the partial degradation process appears in the 1H NMR spectra of complexes 5– 10. Comparison of the integral of this signal with that of the broad resonance in the aromatic region indicated that only one carborane cage has been partially degraded. Nucleophilic attack is expected to occur on the carborane cluster of the bisphosphane ligand, rather than on that of the dithiolate. We confirmed this by X-ray studies (see below). The phosphorus atoms of the bis-phosphane appear as singlets in the 31P NMR spectra of complexes 5–10 at about 85 (M = Pd: 5, 7, and 9) or 65 ppm (M = Pt: 6, 8, and 10). These resonances are shifted to lower field relative to the starting material [M{(PPh2)2C2B10H10)}(S2C2B10H10)]. The chemical shift of the PPh3 ligand depends on M’: about 35 ppm for M’ = Au, about 15 ppm for M’ = Ag and 4 ppm (M = Pd: 9) or 4 ppm (M = Pt: 10) for M’ = Cu. Complexes 7 and 8 display one singlet and two doublets in their 31P{1H} NMR spectra. The singlet corresponds to the bis-phosphane, and the two doublets are as-
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Full Paper signed to coupling of the P atoms of the PPh3 ligand to the Crystal structure determinations silver isotopes 109Ag and 107Ag. With the aim of obtaining analogous complexes displaying The structures of complexes 5–7, 9, and 11 were determined NiM’ (M’ = Au, Ag, Cu) interactions, we carried out the reacby X-ray crystallography (Figure 3). They confirmed partial degtion of [NiCl2{(PPh2)2C2B10H10}] with (SH)2C2B10H10. It led to a mixradation of the carborane cage of the bis-phosphane ligand, ture of complexes which included the expected product, but and all of them show d8–d10 metallophilic interactions[6] partial degradation of the bis-phosphane was observed. As it (Table 1). The only crystal structures reported of heterometallic was not possible to obtain pure samples of [Nicomplexes with carborane ligands containing Group 11 and {(PPh2)2C2B10H10}(S2C2B10H10)], we tried a one-pot synthesis to obtain complexes with NiM’ (M’ = Au, Ag, Cu) interactions. Table 1. Bond lengths [] for [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)]. The reaction of NiCl2·6 H2O with Bond Compound (M/M’) (PPh2)2C2B10H10, (SH)2C2B10H10, 5 (Pd/Au) 6 (Pt/Au) 7 (Pd/Ag) 9 (Pd/Cu) 11 (Ni/Au) and [AuCl(PPh3)] in refluxing [a] 2.2592(12), 2.2689(18), 2.2517(11), 2.2527(13), 2.1700(12), MP methanol gave the expected 2.2851(12) 2.2417(18) 2.2600(11) 2.2569(13) 2.2023(13) product 11. The one-pot reacMS 2.3349(11), 2.3331(19), 2.3846(13), 2.4027(13), 2.1894(12), tion of [NiCl2{(PPh2)2C2B10H10}] 2.3905(12) 2.3629(18) 2.4035(11) 2.4172(13) 2.2296(12) 2.2599(12) 2.242(2) 2.3577(11) 2.1903(14) 2.2659(12) M’P[b] with (SH)2C2B10H10 and [AuClM’S 2.3282(11) 2.3338(12) 2.4918(10), 2.3172(13), 2.3488(11) (PPh3)] in refluxing methanol/ 2.8336(13) 2.4187(15) ethyl acetate gave similar yields. MM’ 3.2618(12) 3.2251(7) 2.9498(8) 2.7519(9) 3.0206(8) The 31P{1H} NMR spectrum of 11 0.00609 0.0885 0.0311 0.0060 0.0746 M[c] a[d] 93.8 86.5 76.9 104.1 84.5 displays one resonance at 74.5 ppm, due to the phospho[a] Phosphorus atoms of the bis-phosphane. [b] Phosphorus atom of PPh3. [c] Deviation of M from the plane built from P2, S1, S2. [d] Angle between planes 1 and 2: plane 1, built from atoms P1, P2, S1, and S2; plane 2, rus atoms of the bis-phosphane built from atoms: M’, P3, and S. P1 and P2: phosphorus atoms of the bis-phosphane; P3: phosphorous atom of and another at 34 ppm, correPPh3. sponding to the PPh3 ligand.
Figure 3. Molecular diagrams of complexes 5 (a), 6 (b), 7 (c), 9 (d), and 11 (e) showing the atom-labelling schemes. Hydrogen atoms have been omitted for clarity. Ellipsoids represent 50 % probability levels. Chem. Eur. J. 2014, 20, 3120 – 3127
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Full Paper Group 10 metal atoms are metallacarborane complexes[7] and the species [AgNiCl2{(PPh2)2C2B10H10}{(PPh2)2C2B9H10}],[8] in which both bis-phosphanes are coordinated in a chelating mode. The nido bis-phosphane is coordinated to the silver centre and the closo bis-phosphane to the Ni atom. No metal–metal interaction was reported for any of them. The PtAu distance in 6 resembles the shortest PtAu intermetallic interactions in the complexes discussed in the introduction,[4] whereas the PdCu and PdAg distances in 7 and 9 are shorter than those reported for such complexes. The M(d8) metal centres have a square-planar coordination environment. The main distortion is due to the bite angles of the chelating bis-phosphane and dithiolate ligands (Table 2).
Table 2. Bond angles [8] for complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)]. Compound (M/M’)
P[a]-M-P[a]
S-M-S
S-M’-P[b]
5 (Pd/Au) 6 (Pt/Au) 7 (Pd/Ag) 9 (Pd/Cu) 11 (Ni/Au)
82.75(4) 83.82(7) 85.57(4) 85.47(5) 84.79(5)
90.75(4) 91.03(6) 87.73(4) 84.92(5) 95.41(5)
175.44(3) 176.67(7) 156.24(4), 126.96(4) 141.41(5), 131.82(5) 176.27(5)
[a] Phosphorus atoms of the bis-phosphane. [b] Phosphorus atom of PPh3.
The S-M(d8)-S angles range between 95.41 and 84.928, and the P(bis-phosphane)-M(d8)-P(bis-phosphane) angles between 85.55 and 82.758 (Table 2). The M(d10) centres in 5, 6, and 11 are coordinated to the phosphorus atom of the PPh3 ligand and one of the sulfur atoms of the dithiolate in a distorted linear coordination mode. This distortion probably arises mainly from the M(d8) M(d10) metallophilic interaction (see Tables 1 and 2). For compound 7 a short distance of the silver atom to the other sulfur atoms of the dithiolate and a larger distortion from the linear geometry are observed compared to those of complexes 5, 6, and 11. In complex 9 the copper centre is coordinated to both sulfur atoms of the dithiolate, and the geometry of the copper centre can be described as highly distorted trigonal planar.
Figure 4. DRUV spectra of [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)].
Table 3. DRUV maxima, steady-state luminescence data, and lifetimes for complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] (5–11) in the solid state at 77 K. DRUV [nm]
lEm[a](lEx)[b] [nm]
t[c] [ms]
5 (Pd/Au) 6 (Pt/Au) 11 (Ni/Au) 7 (Pd/Ag) 8 (Pt/Ag) 9 (Pd/Cu) 10 (Pt/Cu)
310, 420 279, 365 320, 400, 500 305, 400 300, 415 267, 324 300, 400
630 620 600 615 610 650 600
39.7 43.1 55.6 96.6 26.9 61.2 83.4
(420) (400) (420) (420) (420) (380) (400)
[a] lEm = emission maximum. [b] lEx = excitation maximum. [c] Data were fitted to a first-order exponential decay (R2 = 0.97–0.99).
Photophysical studies The diffuse-reflectance (DR) UV spectra of complexes 5, 7, 8, and 10 exhibit similar patterns. They show a broad band with maxima between 267 and 320 nm and a shoulder with a maximum between 324 and 420 nm (Figure 4, Table 3). Complex 11 displays another shoulder at about 500 nm, which spreads to 610 nm. The spectra of complexes 6 and 9 follow the same pattern, but are shifted to higher energies. The most intense band appears at about 270 nm, and the shoulder at 324 nm. The bands at higher energies may be attributed to the phosphane aryl substituents, whereas that at lower energies may be due to metallophilic interactions or to charge-transfer transitions, which could involve the metal centres (d8 and/or d10) and the ligands (bis-phosphane and/or dithiolate). Chem. Eur. J. 2014, 20, 3120 – 3127
Complex (M/M’)
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The mononuclear complexes 1–4 are non-luminescent. Complexes 5–11 are not emissive in the solid state at room temperature. At 77 K they display emissions in the red region (620 nm) upon excitation at about 400 nm (Table 3). The lifetimes, in the microsecond range, and the Stokes shifts indicate a phosphorescent nature of the emission. The emission spectra display similar profiles for all complexes, although for compound 11 a structured band which spreads to 800 nm is observed (Figure 5). The analysis of the data in Table 3 suggests that the emission is not dependent on the metallophilic d8–d10 interaction. Thus, we propose that charge-transfer transitions are responsible for the luminescence. With the aim of elucidat-
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Figure 5. Emission spectra of [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)].
ing which ligand (dithiolate and/or bis-phosphane) and which metal centre (d8 and/or d10) are involved in such transitions, calculations were carried out in order to visualise the orbitals and make a proposal of how the transitions take place. Theoretical studies Complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (5, 6, and 11) were selected for a computational analysis. For all of the complexes, the crystallographic structures were used as models. The electronic structures of the complexes were obtained by single-point DFT calculations on model systems built up from the X-ray structures with the aim of analysing the frontier molecular orbitals involved in the electronic transitions responsible for the phosphorescence. Figure 6 shows a selection of the frontier orbitals. The HOMO2 for 5 and 6 and HOMO for 11 have thiolate and metal (d8) contributions. Electron delocalisation on the carborane cage was found for the HOMO of 5 and 6 and HOMO2 of 11. A predominant contribution of s-antibonding orbitals of the d8 metal centre and the dithiolate and bis-phosphane ligands in the LUMO orbitals is observed for the three complexes. An important point is that the metallophilic d8–d10 interaction does not make a relevant contribution to the frontier orbitals. This is in agreement with the emissive behaviour observed for the complexes, which does not seem to be dependent on the substitution of the d8 or d10 metal centre. Since the lifetimes and Stokes shifts point to a phosphorescent nature of Chem. Eur. J. 2014, 20, 3120 – 3127
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Figure 6. Selection of frontier molecular orbitals in [M{(PPh2)2C2B9H10}{S2C2B10H10}Au(PPh3)].
the emissions, the TDDFT method was employed to analyse the first singlet!triplet transitions for complexes 5, 6, and 11 and the molecular orbitals involved in such transitions. By comparing the calculated vertical excitation and experimental excitation wavelengths, we can propose that such a transition is responsible for the luminescence. Table 4 lists the more important orbitals involved in this transition. We note that the calculated singlet!triplet excitation energies are lower than the corresponding experimental values. Calculations at this qualitative level do not allow any definitive conclusion about MO energy levels, and the relation between excitation energy and differences in MO energies is only approximately correct. From the data of Table 4 and Figure 6 we can attribute the origin of the luminescence to a charge-transfer transition from
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Table 4. Calculated vertical excitation (lT) and experimental excitation (lEx) energies for complexes [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)]. Compound (M/M’)
lEx [nm/eV]
lT [nm/eV]
Transition
5 (Pd/Au) 6 (Pt/Au) 11 (Ni/Au)
420/2.95 400/3.10 420/2.95
587/2.10 490/2.52 571/1.42
HOMO1(269)!LUMO(271) HOMO(270)!LUMO(271) HOMO1(269)!LUMO(271)
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Full Paper the ligand (L, nido-carborane) to the metal–ligand group “S2M(d8)-P2” (ML’) (LML’CT transition) for complex 6 (M = Pt), and for complexes 5 (M = Pd) and 11 (M = Ni) to charge transfer from the metal [M(d8)] to the metal–ligand group “S2-M(d8)-P2” (ML’) (MML’CT charge transfer). The different origins of the emissive behaviour could be related to the different electronic character of the d8 metal centre, as Pt has the more stable d orbitals.
Conclusion A new family of red emitters of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M’(PPh3)] [M = Pd, Pt; M’ = Au, Ag, Cu] and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] has been synthesised. The complexes exhibit a fluorophore ligand (nido-carborane bis-phosphane), a dithiolate (which may be responsible for metal-to-thiolate or thiolate-to-metal charge-transfer transitions) and d8 M(Ni, Pd, Pt)–d10 M’(Cu, Ag, Au) interactions, which also may lead to emissive behaviour. Calculations for [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M = Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)-to-“P2-M(d8)-S2” group (ML’) charge-transfer (LML’CT) transitions for M = Pt and to metal [M(d8)]-to-“P2-M(d8)-S2” group (ML’) charge-transfer (MML’CT) transitions for M = Ni, Pd.
Experimental Section General comments (SH)2C2B10H10,[9] (PPh2)2C2B10H10,[10] [MCl2{(PPh2)2C2B10H10}] [M = Pd,[5a] Pt,[5b] Ni[11]], [AuCl(PPh3)],[12] [Ag(OTf)(PPh3)],[13] and [Cu(NO3)(PPh3)2][14] were synthesised according to published procedures. Other reagents and solvents were used as received. Solution 1H and 31P NMR spectra were recorded with Bruker Avance 400 and Bruker DPX 300 spectrometers. If not specified, the 400 MHz spectrometer was used. The chemical shifts were referenced to residual resonances of protiated solvent and external 85 % H3PO4 in the 1H and 31P spectra, respectively. Mass spectra were determined on a Bruker APEX-Qe ESI FT-ICR instrument in the ESI + mode. DRUV spectra were recorded on Unicam UV-4 spectrophotometer equipped with a Spectralon RSA-UC-40 Labsphere integrating sphere. The solid samples were mixed with dried KBr to obtain a homogeneous powder. The mixtures were placed in a homemade cell equipped with quartz window. The intensities are given in Kubelka–Munk units. Steady-state photoluminescence spectra were recorded on a HORIBA Jobin Yvon Fluorolog FL-3-11 spectrometer with band pathways of 3 nm for both excitation and emission. Phosphorescence lifetimes were recorded with a Fluoromax phosphorimeter accessory containing an UV xenon flash tube.
Synthesis [PdCl2{(PPh2)2C2B10H10}][M=Pd (1), M = Pt (2)]: [MCl2(NCPh)2] (0.1 mmol, M = Pd: 38.4 mg, M = Pt: 47.2 mg) was added to a solution of (PPh2)2C2B10H10 (0.1 mmol, 50.9 mg) in dichloromethane (20 mL). The solution was stirred for 2 (M = Pd) or 6 h (M = Pt). Concentration of the solution under reduced pressure and addition of n-hexane led to precipitation of 1 and 2 as yellow solids in 98 and 87 % yield, respectively. Data for 1: elemental analysis calcd (%) for C26H30B10Cl2P2Pd: C 45.26, H 4.38; found: C 44.96, H 4.25; 1H NMR (CDCl3, ppm): d = 1–3 (br m, 10 H, BH), 7.54–7.58 (br m, 8 H, Ph), Chem. Eur. J. 2014, 20, 3120 – 3127
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7.63–7.72 (br m, 4 H, Ph), 8.21–8.27 (br m, 8 H, Ph); 31P{1H} NMR (CDCl3, ppm): 79.0 (s); IR (cm1): n˜ (BH) = 2560 (s). Data for 2: elemental analysis calcd (%) for C26H30B10Cl2P2Pt: C 40.10, H 3.88; found: C 39.76, H 3.49; 1H NMR (CDCl3, ppm): d = 1–3 (br m, 10 H, BH), 7.56–7.64 (br m, 8 H, Ph), 7.72–7.82 (br m, 8 H, Ph), 8.23–8.28 (br m, 4 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 56.4 (s, J(195Pt,P) = 1876.0 Hz); IR: n˜ (BH) = 2566 cm1 (s). [M{(PPh2)2C2B10H10}(S2C2B10H10)] [M = Pd (3), M = Pt (4)]: An excess of K2CO3 was added to a solution of (SH)2C2B9H10 (0.1 mmol, 20.8 mg) in dichloromethane (20 mL). The resulting suspension was stirred for one hour, and [MCl2{(PPh2)2C2B10H10}] (0.1 mmol, M = Pd: 68.6 mg, M = Pt: 77.6 mg) was added. The mixture was stirred for 3.0 h (M = Pd) or 6.0 h (M = Pt) and filtered through Celite. The resulting solution was concentrated to about 5 mL. Addition of nhexane led to the precipitation of 3 and 4 as pale yellow solids in 78 and 74 % yield, respectively. Data for 3: elemental analysis calcd (%) for C28H40B20P2PdS2 : C 40.74, H 4.88, S 7.77; found: C 41.03, H, 4.98, S 7.70; 1H NMR (CDCl3, ppm): d = 0–3.5 (br m, 20 H, BH), 7.52– 7.55 (br m, 8 H, Ph), 7.60–7.64 (br m, 4 H, Ph), 8.05–8.10 (br m, 8 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 68.6 (s); IR (cm1): n˜ (BH) = 2568 (s). Data for 4: elemental analysis calcd (%) for C28H40B20P2PtS2 : C 36.79, H 4.41, S 7.01; found: C 36.16, H 3.91, S 6.87; 1H NMR (CDCl3, ppm): 0–3 (br m, 20 H, BH), 7.59–7.75 (br vm, 15 H, Ph), 8.05–8.10 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): 59.1 (s, J(195Pt,P) = 1469.2 Hz); IR (cm1): n˜ (BH) = 2561 (s). [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] [M = Pd (5), Pt (6)]: [AuCl(PPh3)] (0.1 mmol, 49.7 mg) was added to a solution of [M{(PPh2)2C2B10H10}{S2C2B10H10}] (0.10 mmol, M = Pd: 78.9 mg, M = Pt: 91.0 mg) in ethanol (20 mL). The mixture was heated to reflux for 2 h (M = Pd) or 3 h (M = Pt). The solids that precipitated were collected by filtration and washed with n-hexane to give 5 (yellow, 81 % yield) and 6 (pale yellow, 62 % yield). Data for 5: elemental analysis calcd (%) for C46H55AuB19P3PdS2 : C 43.37, H 4.35, S 5.03; found: C 43.09, H 4.00, S 4.75; 1H NMR (CDCl3, ppm): d = 2.19 (br s, 1 H, B-H-B), 0–3 (br m, 19 H, BH), 6.99–7.03 (br m, 5 H, Ph), 7.29–7.42 (br m, 10 H, Ph), 7.64–7.78 (br m, 15 H, Ph), 8.02–8.05 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 80.3 (s, bis-phosphane), 34.4 (s, PPh3); IR (cm1): n˜ (BH) = 2560 (s). Data for 6: elemental analysis calcd (%) for C46H55AuB19P3PtS2 : C 40.55, H 4.06, S 4.70; found: C 40.95, H 4.53, S 4.06; 1H NMR (CDCl3, ppm): d = 2.30 (br s, 1 H, B-H-B), 0–3.5 (br m, 19 H, BH), 7.01–7.03 (br m, 5 H, Ph), 7.35–7.72 (br vm, 25 H, Ph), 7.94–7.98 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): 60.1 (s, J(P,195Pt) = 1528.4 Hz, bis-phosphane), 32.7 (s, PPh3); IR (cm1): n˜ (BH) = 2555 (s). [M{(PPh2)2C2B9H10}(S2C2B10H10)Ag(PPh3)] [M = Pd (7), Pt (8)]: [Ag(OTf)(PPh3)] (0.1 mmol, 51.8 mg) was added to a solution of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (0.10 mmol, M = Pd: 78.9 mg; Pt: 91.0 mg) in ethanol (20 mL) . The mixture was heated to reflux for 2 h (M = Pd) or 5 h (M = Pt). During this period a yellow solid precipitated, which was filtered off and washed with n-hexane to give 7 (78 % yield) and 8 (56 % yield). Data for 7: elemental analysis calcd (%) for C46H55AgB19P3PdS2 : C 46.63, H 4.67, S 5.41; found: C 46.82, H 4.78, S 5.10; 1H NMR (CDCl3, ppm): d = 2.08 (br s, 1 H, BH-B), 0–3 (br m, 19 H, BH), 6.91–6.94 (br m, 5 H, Ph), 7.27–7.44 (br m, 10 H, Ph), 7.60–7.69 (br m, 15 H, Ph), 8.06–8.11 (br m, 5 H, Ph); 31P{1H} NMR (300 MHz, CDCl3, ppm): d = 84.4 (s, bis-phosphane), 15.01 (td, J(109Ag,P) = 692.55, J(107Ag,P) = 595.34 Hz, PPh3); IR (cm1): n˜ (BH) = 2568 (s). Data for 8: elemental analysis calcd (%) for C46H55AgB19P3PtS2 : C 43.38, H 4.35, S 5.03; found: C 43.94, H 4.63, S 4.70; 1H NMR (CDCl3, ppm): 2.20 (br s, 1 H, B-H-B), 0–3.5 (br m,
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Full Paper 19 H, BH), 6.94–6.97 (br m, 5 H, Ph), 7.29–7.39 (br m, 10 H, Ph), 7.55– 7.67 (br m, 15 H, Ph), 7.96–8.0 (br m, 5 H, Ph); 31P{1H} NMR (300 MHz, CDCl3, ppm): 62.5 (s J(195Pt,P) = 1515.6 Hz, bis-phosphane), 12.7 (dd, J(109Ag,P) = 716.85, J(107Ag,P) = 615.04 Hz, PPh3); IR (cm1): n˜ (BH) = 2562 (s). [M{(PPh2)2C2B9H10}(S2C2B10H10)Cu(PPh3)] [M = Pd (9), Pt (10)]: A suspension of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (0.10 mmol, M = Pd: 78.9 mg, M = Pt: 91.0 mg) and [Cu(NO3)(PPh3)2] (0.10 mmol, 64.9 mg) in ethanol (20 mL) was heated to reflux for 2 h (M = Pd) or 3 h (M = Pt). The solid that precipitated was filtered off and washed with n-hexane to give 9 (yellow, 77 % yield) or 10 (pale yellow, 52 % yield). Data for 9: elemental analysis calcd (%) for C46H55CuB19S2P3Pd: C 48.44, H 4.86, S 5.62; found: C 48.14, H 4.53, S 5.86; 1H NMR (CDCl3, ppm): d = 2.05 (br s, 1 H, B-H-B), 0–3.5 (br m, 19 H, BH); 6.86–6.78 (br m, 5 H, Ph); 7.38–7.66 (br vm, 25 H, Ph), 8.05–8.10 (br m, 5 H, Ph), 31P{1H} NMR (CDCl3, ppm): d = 87.3 (s, bis-phosphane), 3.9 (s, PPh3); IR (cm1): n˜ (BH) = 2560 (s). Data for 10: elemental analysis calcd (%) for C46H55CuB19P3PtS2 : C 44.95, H 4.51, S 5.21; found: C 44.68, H,4.27, S 5.36; 1 H NMR (CDCl3, ppm): d = 2.15 (br s,1 H, B-H-B), 0–3.5 (br m, 19 H, BH), 7.06–7.20 (br m, 10 H, Ph), 7.29–7.75 (br vm, 20 H, Ph), 7.99–8.05 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): 62.5 (s, J(195Pt,P) = 1521.5 Hz, bis-phosphane), 3.3 (s, PPh3); IR (cm1): n˜ (BH) = 2578 (s).
Crystallography A crystal of each compound was mounted in inert oil on a glass fibre and transferred to the cold gas stream of a Xcalibur Oxford Diffraction diffractometer (5, 6, 7, 9, and 11) or Bruker Smart Apex CCD (6) equipped with a low-temperature attachment. Data were collected by using monochromated MoKa radiation (l = 0.71073 )
Table 5. X-ray data for complexes 5–7.
formula crystal system space group a [] b [] c [] a [8] b [8] g [8] V [3]/Z 1calcd [Mg m3] m [mm1] F(000) T [8C] 2 qmax measured reflns independent reflns transmission Rint parameters restraints wR(F2, all reflns) R [I > 2s(I)] S D1max [e 3]
[Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (11): Method a: (SH)2C2B10H10 (0.1 mmol 20.8 mg) and [AuCl(PPh3)] (0.1 mmol 49.7 mg) were added to a solution of [NiCl2{(PPh2)2C2B10H10}] (0.10 mmol, 77.3 mg) in methanol (20 mL). The solution was heated to reflux for 4 h. During this time a red solid appeared which was filtered off and washed with n-hexane (60 % yield). Method b: A solution of (PPh2)2C2B10H10 (0.10 mmol, 50.9 mg) and NiCl2·6 H2O (0.10 mmol, 23.7 g) in ethyl acetate/methanol (10/10 mL) was stirred for 10 min, after which (SH)2C2B10H10 (0.1 mmol, 20.8 mg) and [AuCl(PPh3)] (0.1 mmol, 49.7 mg) were added. The solution was heated to reflux for 4 h. During this time a red solid appeared which was filtered off and washed with n-hexane (90 % yield). Elemental analysis calcd (%) for C46H55AuB19NiP3S2 : C 46.27, H 4.64, S 2.68; found: C 46.94, H 4.95, S 2.47; 1H NMR (CDCl3, ppm): d = 2.44 (br s,1 H, B-H-B), 0–3.5 (br m, 19 H, BH); 6.99–7.03 (br m, 5 H, Ph); 7.19–7.23 (br m, 5 H, Ph), 7.33– 7.38 (br m, 5 H, Ph), 7.60–7.74 (br m, 15 H, Ph), 8.04–8.08 (br m, 5 H, Ph); 31P{1H} NMR (CDCl3, ppm): d = 74.5 (s, bis-phosphane); 34.6 (s, PPh3); IR (cm1): n˜ (BH) = 2568 (s).
DFT and TDDFT calculations In all calculations the PBE functional[15] and TURBOMOLE 6.0 program[15c, 16] were used. Single-point DFT[17] calculations were performed on model systems built up from the X-ray structures. The calculated vertical excitation energies were obtained by the timedependent (TD) DFT approach.[18] The Karlsruhe split-valence quality def2-SV(P) basis sets with additional polarization functions on non-hydrogen atoms were used.[19] The resolution of the identity method was used to speed up calculations.[20] The Stuttgart effective core potentials, which include scalar relativistic effects, were used for Ni, Pd, Pt, and Au.[21] The calculations were performed without symmetry constraints. Chem. Eur. J. 2014, 20, 3120 – 3127
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5
6
7
C46H54AuB19P3PdS2 triclinic P1 11.432(2) 15.421(3) 16.144(3) 82.08(3) 84.36(3) 75.12(3) 2718.6(9)/2 1.555 3.225 1254 173 50 10 0882 9546 0.626–0.734 0.0494 653 21 0.0692 0.0288 1.058 1.219
C49H60AuB19P3PtS2 triclinic P 1 11.575(3) 13.389(3) 19.235(5) 78.242(5) 85.205(4) 78.588(5) 2857.8(12)/2 1.631 5.201 1366 173 50 22 149 9988 0.530–0.746 0.0581 734 18 0.0947 0.0431 0.984 1.449
C48H57AgB19Cl6P3PdS2 triclinic P1 12.184(2) 15.788(3) 17.317(4) 72.28(3) 85.81(3) 89.75(3) 3164.1(11)/2 1.494 1.024 1424 173 50 90 662 11110 0.923–0.960 0.0246 807 21 0.0891 0.0376 0.0827 1.599
Table 6. X-ray data for complexes 9 and 11. Compound
9
11
formula crystal system space group a [] b [] c [] a [8] b [8] g [8] V [3]/Z 1calcd [Mg m3] m [mm1] F(000) T [8C] 2 qmax measured reflns independent reflns transmission Rint parameters restraints wR(F2, all reflns) R [I > 2s(I)] S D1max [e 3]
C48H57B19Cl6Cu P3PdS2 triclinic P1
C46H55AuB19NiP3S2 monoclinic P21/n 10.948(2) 28.848(6) 17.306(4) 90 90.53(3) 90 5465.5(19)/4 1.490 3.224 2440 173 50 58 474 8480 0.374–0.627 0.0776 729 0 0.0648 0.0354 0.980 1.473
12.103(2) 15.632(3) 17.342(4) 106.74(3) 93.14(3) 90.95(3) 3135.2(11)/2 1.461 1.060 1388 173 50 88 498 11 008 0.857–0.949 0.0458 801 21 0.1295 0.0545 0.916 2.383
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Full Paper with scan type w. Absorption correction based on multiple scans was applied with the program SADABS.[22] The structure was refined on F2 by using the program SHELXL-97.[23] All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included by using a riding model. Further details of the data collection and refinement are given in Tables 5 and 6. CCDC 961295 (5), 961296 (6), 961297 (7), 961298 (9), and 961299 (11) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements We thank the Ministerio de Economa y Competitividad for project MEC/FEDER CTQ2007-67273-C02-01 and grant BES2008002858 and the Academy of Finland for project 126905. We also thank the Finnish Centre of Excellence in Computational Molecular Science (CMS) and the CSC-IT Centre for Science, Espoo, Finland, for the computer resources provided. Keywords: carboranes · heterometallic complexes luminescence · metal–metal interactions · transition metals
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Received: September 24, 2013 Published online on February 13, 2014
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