Syntheses, crystal structures, and third-order nonlinear optical properties of two novel Mo/Cu/S clusters: [MoS4Cu4(α-MePy)5Br2] · 2(α-MePy)0.5 and {[MoS4Cu4(α-MePy)3Br](μ-Br) · (α-MePy)}n (α-MePy = α-methylpyridine)

Reactions of (NH4)2MoS4 with 4 equiv. of CuBr and 1 equiv. of AgBr in excess α-methylpyridine (α-MePy) gave rise to a pentanuclear cluster [MoS4Cu4(α-MePy)5Br2] · 2(α-MePy)0.5 (1) while those of (NH4)2MoS4 with 4 equiv. of CuBr in α-MePy afforded a one-dimensional polymeric cluster {[MoS4Cu4(α-MePy)3Br](μ-Br) · (α-MePy)}n (2). The X-ray analysis of 1 and 2 showed that the four copper atoms in 1 or 2 are coordinated by a central tetrahedral [MoS4]2− ligand via four μ3-S atoms, giving a MoS4Cu4 fragment with an approximate D2d symmetry. Each fragment in 2 is further interconnected by a μ-Br atom to form a one-dimensional zig-zag chain. The nonlinear optical (NLO) property of 1 and 2 was studied by 35 ps laser pulses, and their third-order nonlinear susceptibility χ(3) was measured by DFWM.