Electronic structure of a beryllium half-sandwich complex, Be(η ~5-C _5H _5)

摘要

Ab initio electron propagator calculations on the electron affinities of the Be (η ~5-C _5H _5) ~+ complex cation and electron detachment energies of the corresponding anion have been performed at the optimized geometry of the ground state of the neutral species. These results, obtained with a basis set that includes many diffuse and polarization functions, provide the relative energies of doublet states of Be(η ~5-C _5H _5). In the former set of calculations, energy differences between the ~2A _1 ground-state and various excited doublet states are associated with promotion of an unpaired electron from the 6a _1 molecular orbital that consists chiefly of s functions on the Be nucleus to higher Be-centered molecular orbitals that exhibit various patterns of interference between s, p, and d functions. Differences between electron detachment energies of the anion provide the energy separation between the radical's ground state and an excited state in which an electron is promoted from ligand-centered π orbitals to 6a _1. Dyson orbitals and pole strengths corresponding to correlated electron binding energies calculated with various diagonal self-energy approximations confirm these qualitative pictures of the electronic structure of the lowest states of Be(η ~5-C _5H _5).