Binuclear complexes of Ni(i) from 4-terphenyldithiophenol†
Binuclear complexes of Ni(I) have been prepared from a 4-terphenyldithiophenol ligand. Steric effects were found to determine the formation of coordination isomeric structures that differ in the nature of metal-to-ligand bonding. Coordination of spatially demanding phosphine ligands PR3, R = C6H6, C6H11, at nickel sites results in a butterfly shaped thiolate-bridged Ni2(μ-S)2 motif. For smaller PMe3, the central π-system of the 4-terphenyl backbone adopts a bis-allyl like μ-syn-η3:η3-C6H4 structure due to significant d-π* Ni(I)-to-ligand charge transfer. Delocalisation indices δ(Ni–Ni) derived from DFT calculations provide a metric to assess the strength of electronic coupling of the Ni sites based on solid state structural data, and indicated less strong electronic coupling for the bis-allyl like structure with δ(Ni–Ni) = 0.225 as compared to 0.548 for the Ni2(μ-S)2 structural motif. A qualitative reactivity study toward CNCH3 as an auxiliary ligand has provided the first insight into the chemical properties of the bimetallic complexes presented.