Hydrocarbon complexes of ruthenium. Part III. Reactions of cycloheptatrienes with ruthenium carbonyl

Abstract

Cycloheptatriene reacts with [Ru₃(CO)₁₂] in heptane to give as major product the cluster complex [Ru₃(CO)₆(C₇H₇)(C₇H₉)], together with the compounds [Ru(CO)₃(C₇H₁₀)], [Ru(CO)₃(C₇H₈)], [Ru(CO)₂(C₇H₈)], and [Ru₂(CO)₆(C₇H₈)]. The complex [Ru₃(CO)₆(C₇H₇)(C₇H₉)], which contains both a cycloheptadienyl ligand and a bridging cycloheptatrienyl ring, reacts with iodine or CX₄(X = Cl or Br) to give the compounds [Ru(X)(CO)₂(C₇H₉)](X = Br or l) and [Ru₂(X)(CO)₄(C₇H₇)](X = Cl, Br, or l). Both [Ru₃(CO)₆(C₇H₇)(C₇H₉)] and [Ru₂(X)(CO)₄(C₇H₇)] contain C₇H₇ rings which are fluxional down to –100°C. Substituted cycloheptatrienes 7R-C₇H₇(R = Me or Ph) yield analogous complexes [Ru₃(CO)₆(C₇H₆R)(C₇H₈R)] with [Ru₃(CO)₁₂]. These in turn give [Ru(I)(CO)₂(C₇H₈R)] and [Ru₂(I)(CO)₄(C₇H₆R)] with iodine. The latter are fluxional with n.m.r. spectra which are limiting at low temperatures; this, together with a knowledge of the ground-state molecular structure of [Ru₂(I)(CO)₄(C₇H₆Ph)], allows an understanding of the degenerate process involved.