Conor A. Dullaghan

Nucleophilic addition reactions of [(polyarene)Mn(CO)3]+ complexes containing naphthalene type ligands

Abstract [(η6-Polyarene)Mn(CO)3]+ complexes containing naphthalene type ligands undergo regioselective nucleophilic addition reactions with H- and C-donors to give moderate to good yields of η5-cyclohexadienyl complexes. Products derived from hydride addition to naphthalene, phenanthrene and acenaphthene complexes have been characterized by X-ray diffraction.

The versatile chemistry of arenemanganese carbonyl complexes

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.

Insertion of manganese into a C–S bond of dibenzothiophene: a model for homogeneous hydrodesulfurization

Coordination of Mn(CO)3+ to a carbocyclic ring of dibenzothiophene activates a C–S bond to reductive cleavage, affording a novel tetramanganese metallathiacycle 5 that reacts with H2 to form a dimanganese complex 9 containing bridging hydride and thiolate ligands; methylation of 5 followed by hydrogenation results in desulfurization of the dibenzothiophene and formation of [Mn(CO)5(SMe)].