Crystal structure and non-linear optical properties of a novel half-open cubane-like cluster [Et4N]3[WOS3(CuI)3(µ2-I)]· H2O

Abstract

The title compound [NEt₄]₃[WOS₃(CuI)₃(µ₂-I)]· H₂O has been synthesized by the reaction of (NH₄)₂WO₂S₂, CuI and Et₄NI. Single-crystal X-ray diffraction data show that the anionic cluster [WOS₃(CuI)₃(µ₂-I)]^3– has a half-open cage structure. Non-linear optical (NLO) properties of the cluster were investigated with a pulsed laser at 532 nm. The cluster exhibits strong NLO absorption and a self-defocusing effect (effective non-linear absorption coefficient, n^eff₂=–5.0 × 10^–18 m² W^–1; effective non-linear refractive index, α^eff₂= 1.0 × 10^–10 mW^–1, when measured for a 2.3 × 10^–4 mol dm^–3 acetonitrile solution). The corresponding effective NLO susceptibility [χ⁽³⁾_eff] of the cluster is 2.6 × 10^–10 esu. The NLO properties of the cluster were compared with those of two analogues, [NEt₄]₃[WOS₃(CuBr)₃(µ₂-Br)]· 2H₂O and [Et₄N]₃[MoOS₃(CuBr)₃(µ₂-Br)]· 2H₂O.