B3LYP density functional theory calculations have been carried out to examine the structural and energetic aspects of β-hydrogen elimination in several metallacyclic complexes of ruthenium and platinum. Factors affecting barriers of the elimination reactions have been examined. It was found that favorable structural arrangements, in which the transferring β-hydrogen is in close proximity to the metal center, for β-hydrogen elimination exist in certain ring conformations of metallacyclic complexes.

Plausible mechanisms for reactions of the ionized O-3 with N-2 are studied by DFT and electron correlation methods. Calculations show that formation of the primary products O-2(+) + N2O and N2O+ + O-2 arises from an intermediate [O-2...ON2](+) in the ground state and its charge-transfer excited state, respectively. New routes to NO2 + NO+ through an intermediate [ON2...O-2](+) and to [ON...NO](+) + O-2 via the reactions of O-3(+) with N2O are proposed.

Density functional theory with the B3LYP functional is used to calculate the equilibrium geometries and harmonic vibrational frequencies of nitryl halogenides XNO2 and XONO (X = F, Cl, Br, I). Stabilities and isomerizations of these isomers are investigated. Dissociation energies of the X-N bond in XNO2 are predicted at the B3LYP/6-311G* and QCISD(T)/ce-pvTZ levels. The electronic transition energies of the most stable XNO2 species have been estimated by time-dependent B3LYP calculations.