Ab initio calculations on first row transition metal hydrides TMHⁿ⁺ and helides ⁽ⁿ⁺¹⁾⁺ (TM = Sc-Cu, n=0-2)

Ab initio metods have been employed to investigate first row transition metal hydrides and helides of form: TMHⁿ⁺(where n=0–2) and TMHeⁿ⁺(where n=1–3), respectively. Multi-configurational SCF and IC-MRCI methods have been used, along with all-electron ROHF-UCCSD(T) methods, in order to compare trends in the bonding of these series. Equilibrium geometries, dissociation energies and vibrational frequencies have been determined for the low-lying electronic states. A comparison with the diatomic first row transition metal hydrides illustrates the limit of isoelectronic approaches and so further highlights the unique binding properties of helium