Synthesis and crystal structures of dimeric W(Mo)/Cu/S and polymeric W/Cu/S neutral clusters with flexible 1,4-bis(3,5-dimethylpyrazol-1-yl)butane as a linker ligand

Reactions of MES₃]²⁻ (M = W, Mo; E = S, O) with CuCl and bbd 1,4-bis(3,5-dimethylpyrazol-1-yl)butane] in DMF affords two new double nest-shape clusters, WOS₃Cu₃Cl(μ-bbd)]₂ (1) and MoOS₃Cu₃Cl(μ-bbd)]₂ (2) and a novel one-dimensional polymeric complex WS₄Cu₂(μ-bbd)]_n (4). The complexes have been characterized by elemental analysis, IR and UV-Vis spectroscopy, and single-crystal X-ray diffraction. In the core structure of the isostructural dimeric MOS₃Cu₃Cl(μ-bbd)]₂ clusters, the copper atoms have a distorted trigonal planar geometry, with CuS₂N and CuS₂Cl core environments. The MOS₃Cu₃] fragments are interconnected by a pair of flexible μ-bbd ligands via their nitrogen donor atoms to form a centrosymmetric macrocyclic twin-nest-shaped cluster in which the two fragments are also linked by direct secondary Cu…Cl interactions. Complex 4 represents the first example of a polymeric heterothiometallic cluster, interconnected by bbd ligands, to be structurally characterized by X-ray crystallography. In the repeat unit of 4, the skeleton of the cluster core CuS₂WS₂Cu] has an essentially linear Cu…W…Cu arrangement. The W atom retains the tetrahedral geometry of the parent WS₄]²⁻ anion. These cluster cores are linked by bbd bridges having alternately two different conformations to construct a zigzag structure. Complexes MoS₄Cu₃Cl(bbd)_0.5]₂ (3) and WS₄Cu₄(NCS)₂(bbd)₂]_n (5) have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy, but we have been unable to grow suitable crystals of 3 and 5 for X-ray analysis.