A molecular orbital study of bonding and ionization energies in pentavalent uranium imide/amide complexes

• Published in: Inorganic chemistry 1992-02, Vol.31 (4), p.577-581
• Main Authors: Bowmaker, G. A, Goerling, A, Haeberlen, O, Roesch, N, Goodman, G. L, Ellis, D. E
• Format: Article
• Language: English
• Subjects: ACTINIDE COMPLEXES; AMIDES; Atomic and molecular physics; BINDING ENERGY; BOND ANGLE; BOND LENGTHS; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); COHERENT SCATTERING; COMPLEXES; DATA; Density-functional theory; DIFFRACTION; DIMENSIONS; ELECTRON SPECTROSCOPY; ELECTRONIC STRUCTURE; Electronic structure of atoms, molecules and their ions: theory; ENERGY; Exact sciences and technology; IMIDES; INFORMATION; IONIZATION; LENGTH; LIGANDS; MOLECULAR ORBITAL METHOD; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PHOTOELECTRON SPECTROSCOPY; Physics; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; SCATTERING; SPECTROSCOPY 400702 > Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials; THEORETICAL DATA; URANIUM COMPLEXES; X-RAY DIFFRACTION
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic00030a010

Discrete variational local density functional (X{alpha}) calculations on the model complexes ((RN)U(NR{sub 2}){sub 3}) (R = H (1), SiH{sub 3} (2)) have been performed in order to investigate the electronic structure of uranium amido/imido complexes. Special emphasis is placed on the energy ordering of the highest lying levels formed by U 5f orbitals and by out-of-plane N 2p{sub {pi}} orbitals. Orbital relaxations are also estimated by studying the fragments NR and NR{sub 2} with R = H and R = SiMe{sub 3} in order to allow a comparison of the model compounds 1 and 2 with the measured photoelectron spectrum of the complex ((Me{sub 3}SiN)U(N(SiMe{sub 3}){sub 2}){sub 3}). The ionization energies corresponding to the N 2p{sub {pi}} MOs are calculated in the order N 2p{sub {pi}} (amido) < N 2p{sub {pi}} (imido). The calculated level ordering is rationalized by comparing the order of the two types of U-N bonds and the charge distributions of the corresponding ligands. Taking the calculated ordering as well as the character of the molecular orbitals into account, a new assignment of the observed photoelectron spectra is given based on a comparison of He I and He II spectra.