Details

Autor(en) / Beteiligte

• Follett, Angela D
• McNabb, Katherine A
• Peterson, Alicia A
• Scanlon, Joseph D
• Cramer, Christopher J
• McNeill, Kristopher

Titel

Characterization of Co−C Bonding in Dichlorovinylcobaloxime Complexes

Ist Teil von

• Inorganic chemistry, 2007-03, Vol.46 (5), p.1645-1654

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2007

Quelle

MEDLINE

Beschreibungen/Notizen

• This study combines theory and experiment in an examination of Co−C bonding and reductive Co−C cleavage in cobalt dichlorovinyl complexes. It is motivated by the role of dichlorovinyl complexes as intermediates in the dechlorination of trichloroethylene by cobalamin and cobalamin model complexes. A series of seven cis-1,2-dichlorovinyl(L)cobaloxime complexes were prepared (L = m- and p-substituted pyridines; cobaloxime = bis(dimethylglyoximato)cobalt). The complexes were characterized using 1H NMR, 13C NMR, cyclic voltammetry, and X-ray crystallography. Examination of the metrical parameters of the Co−CC unit across the series shows very little change in the CC bond length and a slight increase in the Co−C bond length with increasing electron-donating ability of the pyridine ligand. These structural changes along with electronic structure calculations indicate that Co−C π-bonding is not important in these complexes. The stronger Co−C bonds of vinylcobaloximes compared to those of alkylcobaloximes are best explained by the higher s character at C. Changes in the reduction potential across the series indicate that the pyridine-bound form is the primary electrochemically active species. Theoretical examination of the Co−C cleavage following reduction supports the direct formation of the cis-1,2-dichlorovinyl anion and not the cis-1,2-dichlorovinyl radical.