Partially-occupied d-Orbitals Participating in the Activation of Molecular Oxygen

Abstract

Abstract UV spectroscopic and semiempirical SCFMO investigations have been performed on the partially-occupied (formally unoccupied) d-orbitals participating in the activation of the ground state, 3Σg–O2, with special attention being given to the catalytic activities of onium compounds. The order of the red shifts of the (pz)2→(pz)(d) transition of the onium compounds in an oxygen atmosphere is in satisfactory accordance with those of the magnitude, of the partial occupancy of the d-orbitals and of the catalytic activities of the onium compounds in hydrocarbon oxidations. The dxz (or dyz) and dx2–y2 orbitals are most favorably disposed for the interactions between the Group VI and V onium compounds and the (1πg)-orbital of the 3Σg–O2 respectively. The partial occupation of the formally unoccupied d-orbitals results from the d-π delocalization between the onium central atom and the neighboring atoms of substituents and the counter-anion.