The diabatic couplings between the metal centers in M(Cp)(2)(0/+) (M = Fe, CO; Cp = C5H5) were evaluated using ab initio methods at the Hartree-Fock level of theory. Excellent agreement with the experimental estimate is found for the Fe(Cp)(2)(0/+) couple. For Co(Cp)(2)(0/+), the calculated numbers are substantially higher than the experimental estimates, suggesting that the latter may represent a considerable underestimate (a possibility mentioned in the experimental publication).