Kathryn L. Kunze

The electronic structure of the neutral, mono and di positive transition metal nitrides, ScN, TiN, VN, CrN

Understanding the nature of the transition metal (TM)-main-group-element bond is important in many areas of science. Information on the bonding in neutral TM-main group systems is obtained primarily from matrix isolation experiments [1], gas phase electronic spectroscopy [2] and theoretical calculations [3], while information on the TM ion - main group element bond has been obtained from studies of gas-phase bimolecular reactions [4] of TM ions with organic and inorganic molecules as well as theoretical [5, 6] calculations. The resulting bond energies permit one to systematize and interpret the observed chemistry of these systems and have immediate impact in organometallic chemistry, surface science, catalysis and atmospheric chemistry. Theoretical calculations on the TM-main group bond in coordinately unsaturated molecules have lagged behind the experiments because the extent of electron correlation needed for even qualitatively correct results is significantly raised relative to molecules containing only main group-main group bonds. For example, absent electron correlation, the energy separations between the terms of the low lying s2dN, sdN+1 and dN+2 configurations of the neutral transition metal atoms are seriously flawed. In a molecular calculation this atomic misalignment affects the relative mixture of the TM s, p and d orbitals in the bond and therefore the bond distance and energy. Studies over the last decade by several groups [3, 5, 6] have shown that theoretical studies can provide usefully acc rate descriptions of these systems provided one takes into account the structural correlation energy in the transition-metal-main-group bonds as well as the various spin couplings associated with those bonds and the valence spectator electrons.