Metal-ligand bonds, primary fission

The photochemistry of Co acidoammines upon CTTM excitation can be understood in terms of a mechanism in which homolytic fission of a metal-ligand bond is the primary reaction. 

The primary photochemical reaction of the [MM (CO)i0] (M, M =Mn, Re) complexes in solution has been shown to result in (1) homolytic fission of the metal-metal cr-bond to form M(CO)s radicals, (2) dissociation of a CO ligand to form [MM (CO)9], and (3) non-dissociative relaxation to the electronic ground state [86]. Similar behaviour is shown by other dinuclear carbonyl complexes [87]. 

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