Organosulphur–transition-metal chemistry. Part 6. Reactions of cyclo-octatetraenyl and cycloheptatrienyl thioethers with metal carbonyls

Abstract

The compound C₈H₇SMe has been prepared by treating cyclo-octatetraenyl-lithium with MeSCl. Reaction with [Fe₂(CO)₉] provides tricarbonyliron complexes [Fe(CO)₃(C₈H₇SMe)] and trans-[Fe₂(CO)₆(C₈H₇SMe)]; the former appears to undergo the characteristic oscillatory fluxional motion of such monosubstituted cyclo-octatetraene complexes, but the latter is non-fluxional. Sulphur–C₈H₇ bond cleavage is also evident, in the formation of [Fe₂(CO)₆(µ-SMe)₂] and [Fe₄(CO)₁₂(µ₄-S)(µ-SMe)₂], and of bicyclo-octatetraenyl when C₈H₇SMe and [Ru₃(CO)₁₂] react. Similarly S–C₇H₇ bond cleavage is predominant in reactions of known C₇H₇SR-7 (R = Me or Ph) and new C₇H₇SBu^t-7 (from [C₇H₇][BF₄] and Na[SBu^t]) with a variety of metal carbonyls. Only [Fe₂(CO)₆(µ-SR)₂] is obtained with [Fe₂(CO)₉], and [Mo₂(CO)₂(µ-SBu^t)₂(η-C₅H₅)₂] with [Mo₂(CO)₆(η-C₅H₅)₂], but from [Ru₃(CO)₁₂] complexes, [Ru₃(CO)₆(µ₃-SBu^t){µ₃-(η⁷-C₇H₇)}] and [Ru₂(CO)₄(µ-SR){µ-(η⁷-C₇H₇)}](R = Me or Bu^t) are isolated, containing the components of C₇H₇SR as separate ligands. Fluxional rotation of the C₇H₇ ring in the diruthenium complexes is slowed at –100 °C, shown by n.m.r. spectra which also reveal restricted rotation about the S–Bu^t bond.