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Determination of the electronic structures of metal complexes by the scf‐xα scattered‐wave method
Author(s) -
Johnson K. H.,
Wahlgren U.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560060626
Subject(s) - chemistry , atomic orbital , electronic structure , valence (chemistry) , atomic physics , transition metal , molecular orbital , ligand field theory , valence electron , linear combination of atomic orbitals , wave function , molecular physics , metal , electron , computational chemistry , physics , molecule , ion , biochemistry , organic chemistry , quantum mechanics , catalysis
Electronic structures of the tetrahedral transition‐metal complexes MnO 4 ‐ and Ni(CO) 4 and square‐planar complex CuCl 4 2‐ have been calculated, from first principles, by the self‐consistent‐field X α scattered‐wave (“multiple‐scattering”) method. The stabilizing electrostatic fields of typical crystalline environments have been approximately included for MnO 4 ‐ and CuCl 4 2‐ , and in the latter example spin‐polarized calculations have been carried out. Contour maps of the valence‐orbital wave functions and charge density are presented for MnO 4 ‐ , illustrating the importance of both 2 p σ‐3 d and 2 p σ‐3 d ligand‐metal bonding. In Ni(CO) 4 there is little evidence for the occurrence of “back‐bonding” between the Ni 3 d electrons and unoccupied CO 2σ orbitals. Electronic excitations between occupied valence levels and unoccupied levels have been calculated, utilizing Slater's transition‐state concept, which accurately includes the effects of spin‐orbital relaxation. “Ligand‐to‐metal” excitations are shown to be most important in MnO 4 ‐ and CuCl 4 2‐ , while “metal‐to‐ligand” excitations are most important in Ni(CO) 4 . The calculated transition energies are in good agreement with observed visible and near‐ultraviolet optical properties, in contrast to the poor agreement previously obtained in semiempirical and ab initio LCAO calculations. All of the reported SCF‐ X α scattered‐wave calculations have required relatively small amounts of computer time.