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

Abstract

Solvothermal reactions of H 2SSS (H 2SSS = 1,3,4-thiadiazole-2,5-dithiolate) with CuCN and [WOS 3CuCN] 2− or [W(Mo)S 4] 2− in organic solvents produced three novel 2D layered polymers, namely, [Et 4N][WS 3.5O 0.5Cu 3(CN) 0.5(SSSH 0.5)] ( 1), [Et 4N][WS 4Cu 3(SSS)] ( 2) and [Et 4N] 2[MoS 4Cu 4(CN)(SSSH 0.5) 2] ( 3). X-ray diffraction analyses reveal that in 1 or 3, the nest-shaped clusters {WS(O)S 3Cu 3} or saddle-shaped clusters {MoS 4Cu 4} are linked together by SSS ligands to form a double chain [ WS 3.5 O 0.5 Cu 3 ( SSSH 0.5 ) ] n - 1 / 2 or a zigzag chain [ MoS 4 Cu 4 ( SSSH 0.5 ) 2 ] n - , respectively. The CN − groups bridge the chains in 1 or 3 resulting in the formation of a 2D anionic network. Compound 2 is constructed from T-shaped {WS 4Cu 3} 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.