Ring reversal, sulphur inversion, and 1,3-metal shifts in sulphur-containing six-membered-ring complexes of chromium and tungsten carbonyls
Complexes of the general formula [M(CO)5L](M = Cr or W; L = [graphic omitted]H2,[graphic omitted]H2, and β-[graphic omitted]HME) have been prepared and studied by variable-temperature 1H n.m.r. spectroscopy. Detailed computer syntheses of static and dynamic spectra indicate that the complexes exist in a number of conformations which are interconverted by fluxional processes. These processes are six-membered ligand ring reversal, pyramidal sulphur-atom inversion, and commutation of an M(CO)5 moiety over three sulphur atoms via a 1,3-shift process. Accurate energy barriers (ΔG‡) for all three processes have been calculated. It is interesting to note that only the β-[graphic omitted]HMe complexes undergo the 1,3-shift process at ambient temperature.