Unusual migration of manganese to an arene via protonation of an agostic η3:CH-cyclohexenyl complex

Abstract

Treatment of the agostic compound [Mn(η^3:CH-C₆H₈Ph)(CO)₃]1a with HBF₄·Et₂O in CH₂Cl₂ gave the arene complex [Mn{η⁶-C₆H₅(C₆H₉)}(CO)₃][BF₄]2via migration of the metal from the cyclohexenyl ring to the aryl substituent. Reaction of 2 with the nucleophiles triphenylphosphine and methylmagnesium chloride respectively gave the substitution product [Mn{η⁶-C₆H₅(C₆H₉)}(CO)₂(PPh₃)][BF₄]3 and the addition product [Mn{η⁵-C₆H₅Me(C₆H₉)}(CO)₃]4 as a mixture of isomers. The crystal structure of complex 2 has been determined: triclinic, space group P, a= 9.399(3), b= 10.644(2), c= 8.979(1)Å, α= 93.03(1), β= 116.39(2), γ= 79.45(3)°, R= 0.057 for 1316 independent reflections.