Four W(Mo)/Cu/S complexes containing N-heterocyclic thiones as linkers: Synthesis, structures and optical properties

Reactions of [W(Mo)OnS4−n]2− (n = 0–1) with 2 equiv. of CuSR (R = N-heterocyclic thiones) led to the formation of four new Mo(W)/Cu/S compounds, [Et4N]2[(OWS3Cu2)2(pydt)2] (1), [Bu4N]2[{WS4Cu2}2(pydt)2] (2) (Hpydt = 2-pyridinethiol) and [Bu4N][{MS4Cu2}(dmpymt)] (3, M = W; 4, M = Mo; Hdmpymt = 4,6-dimethylpyrimidine-2-thiol). Single-crystal X-ray diffraction studies reveal that 1 is a novel double butterfly-shaped cluster in which two butterfly fragments {OWS3Cu2} are linked by two μ3-S2− and two pydt− ligands. Compounds 2–4 feature 1D zigzag polymer constructed from linear {CuMS4Cu} building blocks and bridging pydt− or dmpymt− ligands. Compounds 1–4 exhibit interesting emissions with peak maximum at 798, 594, 594 and 672 nm upon excitation at 360, 270, 290 and 290 nm, respectively. The title compounds show optical transitions with band gaps of ∼2.30, 2.59, 2.54 and 2.19 eV for 1–4, respectively.