Stepwise addition of CuNCS onto [Et4N][Tp*WS3]: Design, syntheses, structures and third-order nonlinear optical properties

Abstract

Stepwise reactions of [Et₄N][Tp*WS₃] (1) (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with 1–4 equiv. of CuNCS (and Et₄NBr in the case of three equiv. of CuNCS) afforded the [1 + 1] to [1 + 4] addition products [Et₄N][Tp*WS(μ-S)₂(CuNCS)]·0.5CH₂Cl₂ (2·0.5CH₂Cl₂), [Et₄N][Tp*W(μ₃-S)(μ-S)₂(CuNCS)₂]·ClCH₂CH₂Cl (3·ClCH₂CH₂Cl), [Et₄N]₂[Tp*W(μ₃-S)₃(CuNCS)₃(μ₃-Br)]·1.5aniline (4·1.5aniline), and {[Et₄N][Tp*W(μ₃-S)₃(Cu-μ-SCN)₃(Cu-μ₃-NCS)]}_n (5). Compounds 2–5 were characterized by elemental analysis, IR spectra, UV-vis spectra, ¹H NMR, and single-crystal X-ray crystallography. The cluster anion of 2 contains a [WS₂Cu] core formed by addition of one CuNCS group onto the [Tp*WS₃] species. The cluster anion of 3 has a butterfly-shaped [WS₃Cu₂] core constructed by addition of two CuNCS groups onto the [Tp*WS₃] species. The cluster dianion of 4 consists of a cubane-like [Tp*WS₃Cu₃(μ₃-Br)] core assembled by addition of three CuNCS groups onto the [Tp*WS₃] species followed by filling a μ₃-Br into the void of the incomplete cubane-like [Tp*WS₃(CuNCS)₃] fragment. 5 has a 2D cluster-supported layer network in which each [Tp*WS₃Cu₃] core acting as a pyramidal 3-connecting node interconnects with the [Cu(NCS)₄] units through thiocyanate bridges. In addition, the third-order nonlinear optical (NLO) performances of 2–5 in DMF were also investigated by Z-scan techniques.