Syntheses and characterization of three novel W(Mo)/Cu/S cluster-based layered polymers with 1,3,4-thiadiazole-2,5-dithiolate (SSS): Intriguing coordination modes of SSS

Three novel 2D layered polymers, namely, [Et4N][WS3.5O0.5Cu3(CN)0.5(SSSH0.5)] (1), [Et4N][WS4Cu3(SSS)] (2) and [Et4N]2[MoS4Cu4(CN)(SSSH0.5)2] (3) have been prepared by solvothermal reactions of H2SSS (H2SSS = 1,3,4-thiadiazole-2,5-dithiolate) with CuCN and [WOS3CuCN]2− or [W(Mo)S4]2− in organic solvents. In these complexes, the nest-shaped {WS(O)S3Cu3} core in 1, the T-shaped {WS4Cu3} core in 2 and the saddle-shaped {MoS4Cu4} subunit in 3 serve as metal nodes whereas the SSS ligands function as multi-dentate linkers. The SSS ligand in both 1 and 2 coordinates to five Cu atoms via its exocyclic sulfur and endocyclic nitrogen atoms in an unprecedented fashion, while in 3, it acts as a rare tridentate ligand to connect three Cu atoms. Complexes 1-3 show optical transitions with band gaps of 1.90-2.24 eV.