The versatile chemistry of arenemanganese carbonyl complexes

Abstract

The manganese carbonyl fragment Mn(CO)₃⁺ is easily co-ordinated to a very wide range of aromatic molecules, e.g. benzenes, hydroquinones, naphthalenes, indoles and benzothiophenes. The resulting air-stable [Mn(η⁶-arene)(CO)₃⁺] cations are quite electrophilic, and this is the basis for much interesting and useful chemistry. Carbon-donor nucleophilies ranging from weak to strong add rapidly and regioselectively to the arene to afford thermally stable cyclohexadienyl complexes from which functionalized arenes and cyclohexadienes can be obtained after oxidative removal of the metal. Chemical reduction of [Mn(η⁶-polyarene)(CO)₃]⁺ with or without another metal complex present constitutes a general route to homo- and hetero-nuclear syn- and anti-facial bimetallic complexes with naphthalene-type ligands. Chemical reduction of [Mn(arene)(CO)₃]⁺(arene =η⁶-benzothiophene or η⁵-thiophene) leads to C–S bond cleavage and the formation of novel metallacyclic complexes of relevance to hydrodesulfurization chemistry. These and other aspects of arenemanganese carbonyl chemistry are discussed.