Kinetics and mechanism of the outer-sphere oxidation of metal carbonyl anions with coordination complexes containing chloride

Reactions of metal carbonyl anions, CpFe(CO)2-, Re(CO)5-, Mn(CO)5-, CpMo(CO)3-, CpCr(CO)3-, and Co(CO)4-, with CrCl3.3S (S = THF, CH3CN) and reactions of Mn(CO)5- and Re(CO)5- with [Co(o-phen)2Cl2]ClO4 are reported. Net oxidation/reduction chemistry is observed with formation of metal carbonyl dimers and CrCl2.4S or Co(o-phen)2Cl2. Metal carbonyl halides are also observed and shown to arise from a second reaction of the metal carbonyl dimer with the oxidant. The products and rates are most consistent with outer-sphere electron-transfer reactions. Reactions of CpFe(CO)2- with CpFe(CO)2X (X = Cl, Br, I) are also reported. The rate dependence on X is very small and in the order expected for nucleophilic substitution.