Electronic structure of f{sup 1} actinide complexes. 1. Nonrelativistic and relativistic calculations of the optical transition energies of AnX{sub 6}{sup q{minus}} complexes

Journal Article · Wed May 10 04:00:00 EDT 1995 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic00114a036· OSTI ID:458754

Kaltsoyannis, N; Bursten, B E ^[1]

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1. Ohio State Univ., Columbus, OH (United States)

The ground-state electronic structures of PaX{sub 6}{sup 2{minus}} (X = F, Cl, Br, I), UX{sub 6}{sup {minus}} (X = F, Cl, Br), and NpF{sub 6} have been calculated, using both nonrelativistic implementations of the discrete-variational X{alpha} (DV-X{alpha}) method. A significant amount of metal-ligand covalent bonding is found, involving both 6d and 5f metal orbitals. The 5f contribution to the bonding levels increases significantly from PaX{sub 6}{sup 2{minus}} to UX{sub 6}{sup {minus}} to NpF{sub 6} but remains approximately constant as the halogen is altered in PaX{sub 6}{sup 2{minus}} and UX{sub 6}{sup {minus}}. In contrast, the 6d atomic orbital character of the halogen-based levels increases from UF{sub 6}{sup {minus}} to UBr{sub 6}{sup {minus}} and a similar, through less marked, trend is observed in PaX{sub 6}{sup 2{minus}}. The electronic transition energies have been calculated using the transition state method. The relativistic calculations are far superior to the nonrelativistic ones in both qualitatively and quantitatively describing the electronic spectra. The stabilization of the metal 5f atomic orbitals with respect to the halogen np levels from protactinium to neptunium results in the more energetic f {yields} f transitions in NpF{sub 6} being masked by the onset of a ligand-to-metal charge-transfer band. In the remaining molecules, the f {yields} F transitions in NpF{sub 6} being masked by the onset of a ligand-to-metal charge-transfer band. In the remaining molecules, the f {yields} f transitions occur well removed from charge-transfer bands.

• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-86ER13529
• OSTI ID: 458754
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 10 Vol. 34; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
ACTINIDE COMPLEXES
ANIONS
ELECTRONIC STRUCTURE
GROUND STATES
HALIDES
MATHEMATICAL MODELS
RELATIVISTIC RANGE