Computational chemistry insights in the REDOX Behaviour of Cr and W Fischer carbene complexes

[摘要] An electrochemical study of a series of Fischer carbene complexes containing a hetero-aryl group showed that Cr and W carbenes exhibit different electrochemical behaviour. The Cr carbenes are oxidized in two one electron oxidation processes, namely Cr(0) to Cr(I) and Cr(I) to Cr(II). On the contrary, Fischer carbene complexes of tungsten are directly oxidized from W(0) to W(II). The first reduction process observed for both W- and Cr- carbenes, is a one electron process. A density functional theory (DFT) computational chemistry study of the electronic structure of the Cr- and W-carbenes, showed that the oxidation is metal based and the reduction is located on the carbene ligand. The DFT calculations further showed that the Cr(II) species is a triplet and the W(II) species a closed shell singlet. The DFT calculated energies of the HOMO and LUMO of the neutral carbenes relate linearly to the experimental oxidation and reduction potential, respectively. These mathematical relationships obtained can be used to predict experimentally measured potentials of related Fischer carbene complexes.

[发布机构] Department of Chemistry, University of Pretoria, Private Bag X20, Hatfield; 0028, South Africa^1;Department of Chemistry, University of the Free State, Bloemfontein; 9300, South Africa^2

[效力级别] 数学

[关键词] Electrochemical behaviour;Electrochemical studies;Electron process;Fischer carbene complex;Mathematical relationship;One-electron oxidation;Oxidation and reduction;Reduction process