To further understand whether metal-metal bond cleavage could occur by heterolytic or homolytic pathways, a series of DFT calculations were undertaken. The energies for the homolytic and heterolytic cleavage of the metal-metal bond were calculated for 2a (Scheme 4). These steps were evaluated for structures with CO associated and CO dissociated. While barriers to cleavage are universally high, the energies for the homolytic dissociation were significantly lower (< 50 kcal mol -1 ) compared to the heterolysis. The dissociation energies were calculated without including semiempirical dispersion corrections, as invoking these resulted in deviations from experimental results and over-estimated binding energies. Furthermore, similar barriers for homolysis of Al-Fe bonds have been calculated by Mankad and coworkers for a closely related system. The calculations suggest that the results of cross-over experiments are most likely due to homolysis rather than heterolysis of the metal-metal bond. To further probe this hypothesis, reactions with H2 were conducted with a series of different solvents. Heterolysis results in charge separation and as such, it might be expected that more polar solvents would facilitate this pathway increasing yields at shorter reaction times. The reaction of H2 with 2a in different solvents (benzene, ε = 2.3; THF, ε = 7.6; fluorobenzene, ε = 5.4) led to similar NMR yields for formation of 3a. Given these results, we consider that the homolytic metal-metal bond cleavage to form radical intermediates is more probable to occur compared to the heterolytic version. EPR experiments were performed to probe the potential formation of radical intermediates.