Density functional theory predictions of second-order hyperpolarizabilities of metallocenes

The geometries in the staggered and eclipsed conformations of the metallocenes, M(C5H5)(2) with M = Mn, Fe, Co, Ni, and Ru, have been calculated at the local and nonlocal density functional theory (LDFT and NLDFT) levels. The M-C distance is predicted to be too short at the LDFT level and too long at the NLDFT level. The doublet low-spin states for M = Mn and Co show distortions away from the idealized fivefold symmetries. The low-spin state for M = Mn is predicted to be lower in energy than the high-spin state in contrast to the observed experimental results. The size of the splitting is strongly dependent on the computational level. The values of alpha and gamma were calculated for the various metallocenes. The highest value of gamma was found for M = Co.