Matrix isolation infrared spectra and density functional calculations of the end-on and side-on bonded titanium monoxide-dinitrogen complexes were reported. These species were prepared by the reactions of laser-evaporated titanium monoxide with N-2 or titanium atom with N2O in solid argon. The ground state TiO molecules or Ti atoms reacted with N-2 or N2O to form the endon bonded OTiNN complex spontaneously on annealing. This complex rearranged to the side-on bonded OTi(N-2) molecule upon visible light irradiation. (c) 2005 Elsevier B.V. All rights reserved.