Solid-state synthesis, crystal structure, and effective third-order nonlinear optical properties of (NEt4)3[MoOS3Cu3Br 3(μ2-Br)]·H2O

Abstract

The title compound [NEt4]3[MoOS3CU3Br 3(μ2-Br)]·H2O was synthesized by a solid-state reaction of (NH4)2MoO2S2, CuBr, and Et4NBr at 70°C. Single-crystal X-ray diffraction data show that the anionic cluster [MoOS3(CuBr)3(μ-Br)]3- has a half-open-cage structure which is an intermediate between cubic cage and nest structures. The crystal has an orthorhombic symmetry with a space group of Pnma. Cell parameters are a = 18.648(3) Å, b = 15.156(2) Å, c = 16.226(3) Å, V = 4586 Å3, and Z = 4. The crystal structure was refined to R = 0.061, Rw = 0.053. The cluster exhibits both optical self-defocusing and optical nonlinear absorption (effectively n2 = -2.3 × 10-16 m2 W-1, α2 = 1.6 × 10-10 m W-1 in a 1.9 × 10-3 mol dm-3 acetonitrile solution) as measured with a 7-ns pulsed laser at 532 nm. The corresponding effective third-order nonlinear optical susceptibilities (χ(3)) is 5.4 × 10-10 esu. These nonlinear optical properties of the cluster were compared with those of cubic-cage-shaped and nest-shaped clusters to reveal a qualitative structure/NLO property correlation. © 1995 American Chemical Society.