Tantalum dioxide complexes with dinitrogen. formation and characterization of the side-on and end-on bonded TaO2(NN)x (x = 1-3) complexes.

The reaction of tantalum dioxide molecule with dinitrogen has been studied by matrix isolation infrared spectroscopy. The tantalum dioxide molecules produced from laser evaporation of bulk Ta(2)O(5) target reacted with dinitrogen to form the TaO(2)(eta(1)-NN)(x) (x = 1-3) complexes on annealing, in which the N(2) ligands are end-on bonded to the tantalum metal center. The TaO(2)(eta(1)-NN)(3) complex decomposed to TaO(2)(eta(1)-NN)(2) under infrared irradiation. The TaO(2)(eta(1)-NN)(2) and TaO(2)(eta(1)-NN)(3) complexes rearranged to the less stable TaO(2)(eta(1)-NN)(eta(2)-N(2)) and TaO(2)((eta(1)-NN)(2)(eta(2)-N(2)) isomers under visible light excitation. Both the mono- and bis-dinitrogen complexes were predicted to have (2)A' or (2)A(1) ground states arising from the (2)A(1) ground state of TaO(2), whereas the two tridinitrogen complexes were predicted to have (2)B(2) ground states with C(2v) symmetry, which are derived from the (2)B(1) excited state of TaO(2).