Syntheses, structures and spectroscopy of new heteroselenometalates

[PPh4]2[MoSe4] and [PPh4]2[WSe4] react with two equivalents of AuCN in CH3CN to afford [PPh4]2[(NC)Au(μ-Se)2-Mo(μ-Se)2Au(CN)] · CH3CN (bd1) and [PPh4]2[(NC)Au(μ-Se)2Au(CN)] · CH3CN (bd2), respectively. Compounds 1 and 2 are isostructural. Compound 1 crystallizes in the triclinic space group P1 with two formula units in a cell dimensions a=13.181(4), b=14.239(4), c=14.684(4) A, α=73.00(3), β=73.66(2), γ=79.06(2)° at 113 K. Full anisotropic refinement of the structure of 1 on F2 led to a value of R1=0.0562 for those 9075 data having Fo2 . 2σ(Fo2). The [(NC)Au(μ-Se)2Mo(μ-Se)2Au(CN)]2− anion of 1 comprises two AuCN fragments ligating the opposite edges of a tetrahedral [MoSe4]2− moiety. Compounds 1 and 2 exhibit an IR band at 2250 cm−1 that may be assigned to a CN stretching mode of the CH3CH solvate; such a solvate molecule was found in the crystal structure of 1. The 77Se NMR spectra show a resonance at 1104 ppm for 1 and 832 ppm for 2. Addition of excess PME2Ph to the same solutions that produce 1 and 2 results in the formation of [PPh4][(Me2PhP)Au(μ-Se)2MoSe2] (3) and [PPh4][(Me2PhP)Au(μ-Se)2WSe2] (4), respectively. Compounds 3 and 4 are not isostructural. Compound 3 crystallizes in the monoclinic space gorup Cc with four formula units in a cell of dimensions a=21.912(4), b=9.809(2), c=15.959(3) A, β=100.79(3) at 113 K. Full anisotropic refinement of the structure of 1 on F2 led to a value of R1=0.0481 for those 6851 data having Fo2 > 2σ(Fo2). Compound 4 crystallizes in the triclinic space group P1 with two formula units in a cell of dimensions a=11.315(2), b=13.053(3), c=14.173(3) A, α=103.59(3), β=103.55(3), γ=114.75(3)δ at 113 K. Full anisotropic refinement of the structure of 4 on F2 led to a value of R1=0.0414 for those 7825 data having Fo2 > 2σ(Fo2). The [(Me2]PhP)Au(μ-Se)2MoSe2]− anion of 3 and the [(Me2PhP)Au(μ-Se)2WSe2]− anion of 4 comprise an [(Me2PhP)Au]+ fragment ligated across an edge of a tetrahedral (MSe4]2− moiety. [PPh4]2[MoSe4] and [PPh4]2[WSe4] react with one equivalent of AuCN in CH3CH to afford [PPh4]2[(NC)Au(μ-Se)2MoSe2] (5) and [PPh4]2[(NC)Au(μ-Se)2WSe2] (6), respectively. Compounds 5 and 6 are isostructural. Compounds 5 crystallizes in the monoclinic space group C2/c with four formula units in a cell of dimensions a=11.234(15), b=20.329(28), c=20.046(28) A, β=91.81(5)° at 113 K. Full anisotropic refinement of the structure of 5 on F2 led to a value of R1=0.0457 for those 4003 data having Fo2 > 2σ(Fo2). The [(NC)Au(μ-Se)2MoSe2]2− anion of 5, which has a crystallographically imposed twofold axis, comprises an AuCN fragment ligated across an edge of a tetrahedral [MoSe4]2− moiety. The reaction of [PPh4]2(NC)Cu(μ-Se)2MoSe2] with one equivalent of AuCN in CH3CN produces a precipitate that is then redissolved through reaction with an excess of PMe2Ph to afford [PPh4][(Me2PhP)2Cu(μ-Se)2MoSe2] (7). Compound 7 crystallizes in the monoclonic space group P11/c with four formula units in a cell of dimensions a=9.975(1), b=30.391(7), c=14.541(6) A, β=109.66(3) at 113 K. Full anisotropic refinement of the structure of 7 on F2 led to a value of R1=0.0305 for those 5205 data having Fo2 > 2σ(Fo2). The [(Me2PhP)2Cu(μ-Se)2MoSe2]− anion of 7 comprises an [(Me2PhP)2Cu]+ fragment ligated across an edge of the [MoSe4]2− moiety to provide a tetrahedral geometry about the Cu atom. The NMR, IR and UV-Vis spectroscopic data for these compounds are consistent with their solid-state structures.