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

Solvothermal reactions of H2SSS (H2SSS = 1,3,4-thiadiazole-2,5-dithiolate) with CuCN and [WOS3CuCN](2-) or [W(Mo)S-4](2-) in organic solvents produced 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). X-ray diffraction analyses reveal that in I or 3, the nest-shaped clusters {WS(O)S3Cu3} or saddle-shaped clusters {MoS4Cu4} are linked together by SSS ligands to form a double chain [WS3.5O0.5Cu3(SSSH0.5)](n)(-1/2) or a zigzag chain [MoS4Cu4(SSSH0.5)(2)](n)(-), respectively. The CN- groups bridge the chains in I or 3 resulting in the formation of a 2D anionic network. Compound 2 is constructed from T-shaped {WS4Cu3} subunits and SSS, also producing a 2D anionic sheet structure. The SSS ligand in 1 or 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 ranging from 1.90 to 2.24 eV. (C) 2007 Elsevier Ltd. All rights reserved.