Pyramidal inversions and 1,2-metal shifts in pentacarbonyl-chromium, -molybdenum, and -tungsten derivatives of dialkyl disulphides and dialkyl diselenides. A nuclear magnetic resonance investigation

Abstract

Variable-temperature ¹H n.m.r. spectra of the mononuclear complexes [M(CO)₅(Me₃SiCH₂EECH₂SiMe₃)](M = Cr, Mo, or W;E = S or Se) have established the occurrence ot two distinct internal dynamic phenomena. The co-ordinated S or Se atom undergoes facile pyramidal inversion whilst at above-ambient temperature a novel 1,2-metal shift between the adjacent pair of chalcogen atoms of the ligands occurs. Energy data for both processes have been computed by total n.m.r. band-shape analyses.