Reactions of metal carbonyl derivatives. Part XIX. Halogenation studies of di-µ-alkylthio- and di-µ-arylthio-bis(tricarbonyliron) and their substituted derivatives

Abstract

Treatment of [{Fe(CO)₃(SR)₂,](R = Me, Et, Prⁱ, or Ph) and [{Fe(CO)₂(SR′)}₂(Ph₂PCH₂PPh₂)](R′= Me, Et, or Ph) with iodine produces neutral products of the type [{Fe(CO)₃I(SR)}₂] and [{Fe(CO)₂I(SR′)}₂,(Ph₂PCH₂PPh₂)] respectively. In contrast reaction of [Fe₂(CO)₅L(SMe)₂](L = PPh₃, AsPh₃, or SbPh₃), [{Fe(CO)₂L′(SR)}₂][R = Me or Ph; L′= PEt₃, PPh₃, P(OMe)₃, or P(OPh)₃], [Fe(CO)₃(SR′)₂{Fe(CO)(Ph₂PC₂H₂PPh₂)}](R′= Me or Bu^t), and [Fe₂(CO)₃{P(OPh)₃}₃(SR″)₂](R″= Me or Ph) with this reagent under the appropriate conditions affords the ionic species [Fe₂(CO)₅IL(SMe)₂]⁺, [{Fe(CO)₂L′(SR)}₂l]⁺, [Fe(CO)₃I(SR′)₂{Fe(CO)(Ph₂PC₂H₂-PPh₂)}]⁺, and [Fe₂(CO)₃I{P(OPh)₃}₃(SR″)₂]⁺ respectively, each containing a bridging iodo-group. The reaction of [Fe₂(CO)₆{(SCH₂)₂}] with iodine also gives an ionic compound, shown to have the stoicheiometry [Fe₃(CO)₆l₅{(SCH₂)₂}]. The non-formation of the neutral product [Fe₂(CO)₂I₂{(SCH₂)₂}] in this reaction is attributed to steric effects. The reactivity of the various ionic species towards iodide ions is discussed and a mechanism for the formation of the neutral iodo-compounds via bridging halogeno-intermediates is described. The i.r., n.m.r., and Mössbauer spectroscopic data are discussed in terms of possible structures.