Philip F. Souter

An infrared spectroscopic and density functional investigation of dinitrogen activation by group IV metal atoms

Reactions of laser-ablated Ti, Zr, and Hf atoms with N2 in excess argon and excess dinitrogen have produced the MN and (N2)xMN molecules in addition to M(μ–N)2M with no dinitrogen bond. Evidence is presented for simple η1–N2 and higher complexes for each metal. The observation of cyclic Ti(N2) and Zr(N2) molecules with N–N stretching frequencies at 1125.9 and 1022.8 cm−1, respectively, indicate significant activation of the dinitrogen bond. The identification of product molecules is based on isotopic substitution and the results of density functional theory frequency calculations.

INFRARED SPECTRUM OF CCH+ IN SOLID ARGON AND NEON

Laser-ablation of over ten different transition, lanthanide, and actinide metals with concurrent codeposition of acetylene/argon samples at 7 K produced metal independent absorptions for CCH, CCH−, C4H, and C4H2, in agreement with previous matrix isolation work, and a sharp new 1820.4 cm−1 band. Isotopic substitution showed this band to be due to a largely C–C stretching mode of a species with one H and two inequivalent carbon atoms. The same species were observed in solid neon samples at 4 K, and the neon matrix counterpart of the new band was found at 1832.2 cm−1. When CO2 was added to serve as an electron trap, the yield of CCH− at 1772.8 cm−1 decreased and the 1832.2 cm−1 band increased relative to CCH at 1837.9, 1835.0 cm−1. Quantum chemical calculations at the coupled-cluster and density functional levels predict the C–C stretching mode of CCH+ between this mode for CCH and CCH− and support assignment of this new infrared absorption to the CCH+ cation in solid argon and neon.

An infrared spectroscopic and quasirelativistic theoretical study of the coordination and activation of dinitrogen by thorium and uranium atoms

The reactions of laser-ablated thorium and uranium metals in condensing pure dinitrogen streams as well as argon/dinitrogen mixtures have provided spectroscopic evidence for the presence of several previously uncharacterized actinide metal nitrides and dinitrogen complexes. Infrared spectra of the matrix isolated product species indicate that thorium and uranium atoms have a significant bond weakening effect on dinitrogen upon initial complexation and in some cases complete dinitrogen bond cleavage is observed. In the reactions of laser-ablated thorium and uranium atoms with pure dinitrogen, the primary products are the metal mononitride (M-N), the metal dinitride (N–M–N), and in the uranium reactions, two dinuclear products U(μ-N)2U and NU(μ-N)2U. In the reactions of thorium with dinitrogen in argon, the primary products are N–Th–N, Th(μ-N)2Th, and the dinitrogen complexes Th-η1-N2 and Th-η1:η1-(N2)2. The complete ground-state electronic structure and vibrational spectrum of each product molecule has bee...

A matrix isolation FT–IR and quasirelativistic density functional theory investigation of the reaction products of laser-ablated uranium atoms with NO, NO2 and N2O

The reaction products of laser-ablated uranium atoms with nitrogen oxide reagent gases were trapped in excess argon at 6–7 K. Infrared spectra of the resulting matrices revealed the presence of several new product species. Major bands at 983.6 and 818.9 cm−1 in the infrared spectra of the reaction products of U atoms with 14N16O are due to the U–N and U–O stretching vibrations, respectively, of the linear NUO molecule. Weaker absorptions at 845.9 cm−1 and 718.3 cm−1 in similar experiments are indicative of a “T” shaped NUO2 species. A weaker 1017.0 cm−1 band provides evidence for the cation/anion pair [NUO]+[NO]−. Several possible products of the reaction of uranium atoms with nitrogen oxides have been further characterized by quasirelativistic density functional calculations.

Infrared spectra of some uranium oxyfluoride molecules isolated in solid argon

Abstract Reaction of laser-ablated uranium with oxygen/fluorine mixtures or laser-ablated uranium dioxide ceramic with fluorine produces the uranium oxyfluorides molecules UO 2 F 2 , UO 2 F and UOF 4 , which have been isolated in solid argon and identified by virtue of the effects of oxygen isotopic substitution on their infrared spectra.

HF STRETCHING-BENDING COMBINATION BANDS FOR SMALL COMPLEXES IN SOLID ARGON

Infrared spectra of HF (with DF substitution) in solid argon contain weak HF stretching–bending combination bands for N2–HF, (HF)2, and (HF)3 that are higher than the sum of fundamentals. This is in accord with stronger hydrogen bonds upon vibrational excitation of the H–F stretching mode, as observed in the gas phase. Overtone bands were also observed for DF and (DF)2 in solid argon.

ACTIVATION OF CO2 BY LASER-ABLATED GROUP 6 METAL ATOMS

The primary reaction products of laser-ablated group 6 atoms with CO 2 prove to be the insertion products OMCO and O 2 M(CO) 2 (M = Cr, Mo, W) which are isolated in argon matrices and identified by the effects of isotopic substitution on their IR spectra.

IR spectra of uranium hydride molecules isolated in solid argon

The primary reaction products of laser-ablated uranium atoms with dihydrogen (UH, UH2, U2H2, UH3 and UH4) are isolated for the first time in an argon matrix and identified by the effects of isotopic substitution on their IR spectra.