REACTIONS OF YTTRIUM AND LANTHANUM ATOMS WITH NITROGEN - INFRARED-SPECTRA OF THE METAL NITRIDES AND DINITROGEN COMPLEXES IN SOLID ARGON ANDNITROGEN

Laser-ablated Y and La atoms react with nitrogen to produce metal nitr ides and dinitrogen complexes, whereas thermally evaporated Y and La a toms 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-ph ase fundamentals near 800 and 790 cm(-1) respectively for YN and LaN. The (YN)(2) and (LaN)(2) molecules and dinitrogen complexes are also i dentified 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 ar gon containing 2% N-2 and deposition in pure nitrogen. The growth of l igated (YN)(2)(NN)(x) and (LaN)(2)(NN)(x) on annealing suggests that t his nitrogen fixation reaction involves little activation energy.