Substitution in 17-Electron Mononuclear Complexes

The vast majority of ligand substitution studies have been with diamagnetic 18-electron and 16-electron complexes. Because of their general scar- 

Basolo and co-workers recently studied CO substitution in [V(CO)6], which is the only stable homoleptic metal carbonyl radical. With phosphine and phosphite nucleophiles (L) reaction (1) follows a strictly second-order 

The relatively stable 17-electron manganese radical [Mn(CO)3L2], L = P(i-Bu)3 or P(n-Bu)3, follows an associative pathway for L replacement at 20°C in hexane, equation (2)  

This conclusion is indicated from the observation of a second-order rate law, a lack of rate retardation with excess L, and a greater rate with the smaller leaving group, P(n-Bu)3. Carbon monoxide exchange in [Mn(CO)3L2] is also associative, as is the reverse of equation (2) by microscopic reversibility. 

The electrochemical oxidation of [(MeCp)Mn(CO)2L] in MeCN or acetone produces 17-electron radicals that are stable enough to allow an investigation of the mechanistic aspects of equation (3), in which L and L are nitrogen or phosphorus donor ligands/ Equation (3) was found to 

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