Construction of Halide-Bridged Tungsten-Copper-Sulfide Double Cubanelike Clusters from a New Precursor [(Tp*WS2)2(μ-S2)]

Treatment of [Et4N][Tp*WS3] (1) (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with 2 equiv of AgSCN in MeCN afforded a novel neutral compound [(Tp*WS2)2(μ-S2)] (2). Reactions of 2 with excess CuX (X = Cl, Br, I) in MeCN and CH2Cl2 or CHCl3 formed three neutral W/Cu/S clusters [{Tp*W(μ3-S)3Cu3(μ-Cl)}2Cu(μ-Cl)2(μ7-Cl)(MeCN)]2 (3), [{Tp*W(μ3-S)3Cu3}2Br(μ-Br)2(μ4-Br)(MeCN)] (4), and [{Tp*W(μ3-S)3Cu3}2{Cu2(μ-I)4(μ3-I)2}] (5), respectively. On the other hand, treatment of 2 with CuX (X = Cl, Br) in the presence of Et4NX (X = Cl, Br) produced two anionic W/Cu/S clusters [Et4N][{Tp*W(μ3-S)3Cu3X}2(μ-X)2(μ4-X)] (6: X = Cl; 7 X = Br). Compounds 2−7 were characterized by elemental analysis, IR, UV−vis, 1H NMR, electrospray ionization (ESI) mass spectra, and single-crystal X-ray crystallography. The dimeric structure of 2 can be viewed as two [Tp*WS2] fragments in which two W atoms are connected by one S22− dianion. Compounds 3−7 all possess unique halide-bridged double cubanelike frameworks. For 3, two [Tp*W(μ3-S)3Cu3]2+ dications are linked via a μ7-Cl− bridge, two μ-Cl− bridges, and a [Cu(MeCN)(μ-Cl)2]+ bridge. For 4, one [Tp*W(μ3-S)3Cu3(MeCN)]2+ dication and one [Tp*W(μ3-S)3Cu3Br]+ cation are linked via a μ4-Br− and two μ-Br− bridges. For 5, the two [Tp*W(μ3-S)3Cu3]2+ dications are bridged by a linear [(μ-I)2Cu(μ3-I)2Cu(μ-I)2]4+ species. For 6 and 7, two [Tp*W(μ3-S)3Cu3X]+ cations are linked by a μ4-X− and two μ-X− bridges (X = Cl, Br). In addition, the third-order nonlinear optical (NLO) properties of 2−7 in MeCN/CH2Cl2 were investigated by using femtosecond degenerate four-wave mixing (DFWM) technique.