Assembly of two cluster-based coordination polymers with good NLO performance from one NLO-inactive precursor cluster [Et4N][Tp*W(μ3–S)3(CuCl)3]

Abstract

Reactions of the precursor cluster [Et₄N][Tp*W(μ₃–S)₃(CuCl)₃] (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) (1) with 2 equiv of AgSCN produced one 1D [Tp*W(μ₃–S)₃Cu₃]-based coordination polymer [Tp*W(μ₃–S)₃Cu₂Cu(μ–SCN)(μ₃–SCN)]₂·Et₂O (2·Et₂O) while analogous reactions of 1 with Nadca (dca = dicyanamide) formed one 2D [Tp*W(μ₃–S)₃Cu₃]-based coordination polymer [Tp*W(μ₃–S)₃Cu₃(μ_1,5–dca)(μ_1(3),5–dca)]₂·CH₂Cl₂ (3·CH₂Cl₂). Compounds 2–3 were characterized by elemental analysis, IR spectra, UV-vis spectra, ¹H NMR spectra, and the crystal structures of 2·Et₂O and 3·CH₂Cl₂ were determined by single-crystal X-ray crystallography. The structure of 2 consists of the incomplete cubanelike [Tp*W(μ₃–S)₃Cu₃] cores which are interlinked by SCN bridges. Compound 3 contains repeating dimeric [Tp*W(μ₃–S)₃Cu₃₍μ_1(3),5–dca)]₂ units, which are further interconnected by four Cu–μ–dca–Cu bridges to form a 2D layer with a 6³ topology. The third-order nonlinear optical (NLO) properties of 1–3 in DMF were also investigated using femtosecond a degenerate four-wave mixing DFWM technique. The two assemblies 2 and 3 exhibited good third-order NLO performances through connecting the cluster [Tp*W(μ₃–S)₃Cu₃] cores of 1 bearing no NLO properties via thiocyanate or dicyanamide bridges.