Effective core potential studies of lanthanide complexes
- Department of Chemistry, The University of Memphis, Memphis, Tennessee 38152 (United States)
A recently developed compact effective core potential (ECP) scheme for lanthanides [T. R. Cundari and W. J. Stevens, J. Chem. Phys. {bold 98}, 5555 (1993)] is applied to molecular species---the lanthanide trihalides (LnX{sub 3}, Ln=Ce to Lu; X=F, Cl, Br, I). This research is the first ECP study of lanthanide trihalides in which 4{ital f} electrons are explicitly included in the lanthanide valence space. The high-spin 4{ital f}{sup {ital n}} configuration of Ln(III) is described using multiconfiguration (MC) and unrestricted Hartree-Fock (UHF) wave functions. Both methods give excellent agreement with experiment for Ln--X bond lengths, although UHF is faster with no evidence of extensive spin contamination. There is no loss of accuracy from early to late members of the lanthanide series and from the lightest to heaviest halogen for the MC calculations. The root-mean-square difference between MC/ECP Ln--X bond lengths and those estimated from gas-phase experiments is only 0.05 A ({approx}2%). The UHF calculations on LnF{sub 3} yield only three nonplanar minima (CeF{sub 3}, PrF{sub 3}, and PmF{sub 3}). For the three complexes with pyramidal minima, the planar transition states are very close in energy ({Delta}{ital E}{sub UHF}{lt}100 cm{sup {minus}1}), suggesting these complexes will probably be fluxional at ambient conditions. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
- DOE Contract Number:
- FG05-94ER14460
- OSTI ID:
- 122986
- Journal Information:
- Journal of Chemical Physics, Vol. 103, Issue 16; Other Information: PBD: 22 Oct 1995
- Country of Publication:
- United States
- Language:
- English
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