Structural studies on organotransition-metal–bismuth complexes

Abstract

The X-ray single-crystal structures are reported for [BiX{M(CO)₃(η-C₅H₅)}₂](M = W, X = Cl 2; M = Mo, X = Br 3; M = Mo, X = I 4). Compounds 2 and 3 exhibit linear polymeric structures involving intermolecular Bi ⋯ X interactions and are isomorphous with the previously reported [BiCl{Mo(CO)₃(η-C₅H₅)}₂]1. In contrast, the iodide derivative 4 exists in the solid state as a weakly bound dimer. Analysis of Bi-L_III-edge and M-K-edge or L_III-edge extended X-ray absorption fine structure (EXAFS) spectra for [BiCl{M(CO)_y(η-C₅H₅)}₂](M = W or Mo; y= 3 2, 1: M = Fe; y= 2 5) and [Bi{M(CO)₃(η-C₅H₅)}₃](M = W 6 or Mo 7) in solid (1, 2, 5, 7) and solution (1, 5) phases also shows evidence for oligo- or poly-merisation through Bi ⋯ Cl interactions in solid 1, 2 and 5. In tetrahydrofuran (thf) solutions of 1 and 5 these interactions are disrupted, and the monomeric species formed show co-ordination of solvent to bismuth. The BiM₃ species 6 and 7 show metal–metal distances consistent with a pyramidal geometry at bismuth. EXAFS data for BiCl₃8 in the solid and in thf solution showed only indirect evidence for disruption of the weaker Bi ⋯ Cl contacts present in the solid on solvation.