New η5- and μ-(O)-Rh(I) phenoxide complexes: synthesis, characterisation and unconventional reactivity of η5-complexes towards carbon dioxide

The synthesis, analytical and spectroscopic characterisation, and reactivity of three new Rh(I)–phenoxide complexes of formula Rh2(μ-OPh)2(C2H4)4 (1), Rh(C2H4)2(η5-OPh) (2) and Rh(diphos)(η5-OPh) (4) [diphos=1,2-bis(diphenylphosphino)ethane] are reported. Both the η5- and μ-(O) modes of bonding have been found. The η5-complexes are quite air-sensitive. The reactivity towards carbon dioxide is described and the formation of an emicarbonate is reported with the O-bonded phenoxide. A ring carboxylation occurs with η5-complexes.