This paper is the first of a two-part study of the reaction products of laser-ablated lanthanide metal atoms with O 2 . There is general agreement with previous gas-phase and matrix-isolated neutral monoxides of the lanthanide elements. The present results agree with earlier identifications of CeO 2 and PrO 2 and make new assignments for NdO 2 , SmO 2 , EuO 2 , and GdO 2 . In addition, this work provides vibrational frequencies for six LnO + , five LnO -, two LnO 2 + , six LnO 2 -, and two LnO 3species; five (LnO) 2 rings are also reported here for the first time. Low ionization energies for the metals and the LnO molecules facilitate production of the LnO + cations and make electrons available for capture to form molecular anions. The doping of CCl 4 into these samples provides a diagnostic test for the identification of molecular cations and anions by matrix infrared spectroscopy.

Laser-ablation of over 20 different metal targets with concurrent 10 K codeposition of Ar/NO mixtures produces metal independent infrared bands at 1589.3 cm−1 due to (NO)2+, a new absorption at 1221.0 cm−1, and a band set at 1300.3, 1222.7, 884.4 cm−1. The latter bands decrease more on annealing than the 1221.0 cm−1 band. Isotopic substitution (14NO,15NO, 15N18O, and mixtures) shows that these new vibrations involve two equivalent N–O oscillators, which identifies two new (NO)2 species. The excellent agreement with frequencies, intensities, and isotopic frequency ratios from density functional theory calculations substantiates assignment of the 1221.0 cm−1 band to trans-(NO)2− and the three band set to cis-(NO)2−. The observation of a weak combination band at 2492.0 cm−1 further substantiates assignment of the two N–O stretching modes in cis-(NO)2−.

This paper is the second segment of an investigation into the reaction products of laser-ablated lanthanide metal atoms with O2. There is general agreement with previous gas-phase and matrix infrared observations of neutral lanthanide monoxides; the frequencies of monoxide cations and anions are original to this work. The dioxide anion vibrational frequencies of all late lanthanides and neutral frequencies of five of the last seven are reported. In conjunction with the earlier part of this study, it is found that the average vibrational frequencies of the early lanthanide dioxide anions are lower than their neutral counterparts, while those of the late lanthanide dioxide anions are higher. Doping the electron scavenger, CCl4, into these samples provides a diagnostic test for the identification of molecular cations and anions by matrix infrared spectroscopy.

This paper comprises the final section of a two-part study of the small nitride molecules and simple dinitrogen complexes of the lanthanide metals, except promethium. Simple nitrides of the general formulas LnN and (LnN) 2 have been identified for Ln ) Tb, Dy, Ho, Er, Tm, Yb, and Lu. Further elucidation of the Ln(N 2 ) and Ln(NN) 2 complexes is presented. The evidence supports the anticipated conclusion that the later lanthanide metals are less prone to dinitrogen complexation and that the nitrides of the later lanthanide metals require fewer dinitrogen units to achieve saturation.

This paper summarizes the first part of a systematic study of the small nitride molecules and simple dinitrogen complexes of the lanthanide metals except promethium. Simple nitrides of the general formulas LnN and (LnN)2 have been identified for Ln = Ce, Pr, Nd, Sm, Eu, and Gd; LnN2 has been identified for Ln = Ce, Pr, Nd, and Sm. Several dinitrogen complexes of the type Ln(N2), Ln(NN), Ln(NN)2, and Ln(NN) x have also been observed in matrix infrared investigations. The tendency of the identified nitrides to complex dinitrogen is readily determined from experimental data, which provide frequencies for observed fundamentals both before and after dinitrogen complexation. Several reaction pathways to formation of the small nitrides have been explored. The favored pathway to the (LnN)2 molecule involves reduction of N2 by two Ln metal atoms concurrent with complete scission of the N≡N triple bond.