The extent of metal-metal coupling in the mixed-valence complexes [{Ru(NH 3 ) 5 } 2 (μ-L)] 3 + ], where L is 2,5-dimethyl-(Me 2 dicyd 2 ), 2,5-dichloro- (Cl 2 dicyd 2 - ), 2,3,5,6-tetrachloro- (Cl 4 dicyd 2 - ) or unsubstituted (dicyd 2 - ) 1,4-dicyanamidobenzene dianion, was evaluated by comparing theoretical values of metal-metal coupling elements with estimates of the free energy of resonance exchange which were derived from the free energies of comproportionation. Poor agreement was found with the Hush model; however, an excellent correlation was seen with the model of Creutz, Newton and Sutin (CNS). It would appear that the CNS model is remarkably successful in describing the extent of metal-metal coupling for the strongly coupled valence trapped complexes of this study.