Electronic structure of the glyoxalbis(2-hydroxyanil) (gha) ligand in [Co(III)(gha)(PPh(3))(2)](+):
June 28th, 2008 | by admin |Electronic structure of the glyoxalbis(2-hydroxyanil) (gha) ligand in [Co(III)(gha)(PPh(3))(2)](+): radical vs. non-radical states.
The synthesis, structure and spectroscopic properties of a complex salt [Co(III)(gha)(PPh(3))(2)][Co(II)Cl(3)(PPh(3))].C(2)H(5)OH () are reported; gha = glyoxalbis(2-hydroxyanil). This is the first single crystal X-ray structure of a (gha)(2-) complex with a transition element. Though the determined bond parameters and UV-Vis spectroscopic data correlate well with a diradical description for the cation in , detailed electronic structure calculations using density functional theory confirm that [Co(gha)(PPh(3))(2)](+) can be described as a closed shell singlet species which nevertheless displays an interesting electronic structure with significant electron transfer to the formally unoccupied LUMO of the square planar [Co(gha)](+) fragment. It was found that without the phosphine coligands, the [Co(gha)](+) unit has a triplet ground state with the lowest energy singlet diradical state lying only 1 kcal mol(-1) higher in energy. The chemistry of the gha ligand is of interest as a spin diverse redox active system.
Roy AS, Muresan N, Tuononen HM, Rath SP, Ghosh P.
Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata, 103, India. ghoshp_chem@yahoo.co.in.