Theoretical Evidence for the Singlet Diradical Character of Square Planar Nickel Complexes Containing Two o-Semiquinonato Type Ligands
| Autor: | Gottfried Olbrich, Karl Wieghardt, Frank Neese, Vinzenz Bachler |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Diradical
Chemistry Molecular physics Inorganic Chemistry Atomic orbital Computational chemistry Diamagnetism Condensed Matter::Strongly Correlated Electrons Density functional theory Complete active space Symmetry breaking Singlet state Physics::Chemical Physics Physical and Theoretical Chemistry Triplet state |
| Zdroj: | Inorganic Chemistry. 41:4179-4193 |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/ic0113101 |
| Popis: | Density functional theory and complete active space self-consistent field computations are applied to elucidate the singlet diradical character of square planar, diamagnetic nickel complexes that contain two bidentate ligands derived from o-catecholates, o-phenylenediamines, o-benzodithiolates, o-aminophenolates, and o-aminothiophenolates. In the density functional framework, the singlet diradical character is discussed within the broken symmetry formalism. The singlet-triplet energy gaps, the energy gained from symmetry breaking, the spin distribution in the lowest triplet state, and the form of the magnetic orbitals are applied as indicators for the singlet diradical character. Moreover, a new index for the diradical character is proposed that is based on symmetry breaking. All symmetry breaking criteria show that the complexes obtained from o-catecholates and o-benzodithiolates have the largest and the smallest singlet diradical character, respectively. The singlet diradical character should be intermediate for the complexes derived from o-phenylenediamines, o-aminophenolates, and o-aminothiophenolates. The diradical character of all complexes suggests the presence of Ni(II) central atoms. This is also indicated by the d-populations computed by means of the natural population analysis. |
| Databáze: | OpenAIRE |
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