Reactions of Yttrium and Lanthanum Atoms with Nitrogen. Infrared Spectra of the Metal Nitrides and Dinitrogen Complexes in Solid Argon and Nitrogen

Laser-ablated Y and La atoms react with nitrogen to produce metal nitrides and dinitrogen complexes, whereas thermally evaporated Y and La atoms form only dinitrogen complexes. The ligated mononitride complexes (NN) x YN and (NN) x LaN at 771.6 and 761.7 cm -1 in solid nitrogen are identified from nitrogen-15 shifts. These complexes predict gas-phase fundamentals near 800 and 790 cm -1 respectively for YN and LaN. The (YN) 2 and (LaN) 2 molecules and dinitrogen complexes are also identified from nitrogen-15 shifts and result from the reaction of two metal atoms with a single dinitrogen molecule involving the Y(N 2 ) and La(N 2 ) intermediate species. The same saturated (YN) 2 (NN) x and (LaN) 2 (NN) x dinitrogen complexes are prepared on annealing solid argon containing 2% N 2 and deposition in pure nitrogen. The growth of ligated (YN) 2 (NN) x and (LaN) 2 (NN) x on annealing suggests that this nitrogen fixation reaction involves little activation energy.