102920-18-3Relevant academic research and scientific papers
Structure-NMR correlations in halo(ligand)bis(dioximato)cobalt(III) complexes
López, Concepción,Alvarez, Santiago,Solans, Xavier,Font-Altaba, Manuel
, p. 2962 - 2969 (2008/10/08)
A synthetic scheme leading to chloro(ligand)bis(dimethylglyoximato)- and chloro(ligand)bis(diphenylglyoximato)cobalt(III) complexes in good yields is reported for the cases where the ligand is a nitrogenated aromatic base. Substitution reactions of the axial chloro ligand lead to the cyano ligand derivatives. Single-crystal X-ray diffraction and NMR spectroscopic studies were carried out to characterize the above-mentioned complexes. Crystal structures of the following compounds are reported: [Co-(dmgH)Cl(4-NCpy)]·1/3H2O (1), [Co(dmgH)2X(2,6-Me2pz)] (X = Cl (3) and Br (13)), and [Co(dmgH)2Cl(3,5-Me2pzol)] (5), where dmgH = dimethylglyoximate(1-), 4-NCpy = 4-cyanopyridine, 2,6-Me2pz = 2,6-dimethylpyrazine, 2,6-Cl2pz = 2,6-dichloropyrazine, and 3,5-Me2pzol = 3,5-dimethylpyrazole. Compound 1 is orthorhombic, space group P212121, with Z = 4 and unit cell parameters a = 15.690 (3) A?, b = 14.367 (3) A?, and c = 8.320 (2) A?. Compound 3 is monoclinic, space group P21/a, with Z = 4 and unit cell parameters a = 12.827 (2) A?, b = 16.836 (3) A?, c = 8.667 (1) A?, and β = 99.10 (2)°. Compound 5 is monoclinic, space group P21/a, with Z = 4 and unit cell parameters a = 16.139 (3) A?, b = 13.525 (1) A?, c = 8.491 (1) A?, and β = 103.94 (2)°. Compound 13 is monoclinic, space group P21/a, with Z = 4 and unit cell parameters a = 13.019 (2) A?, b = 16.816 (3) A?, c = 8.827 (1) A?, and β = 98.84 (2)°. 1H and 13C NMR chemical shifts of the organic bases show clear correlations with both the position of the atoms relative to the bis(dioximato)cobalt moiety and the wavelength of the Co → dmgH charge-transfer band; these correlations can be rationalized with the aid of the ring-current formalism usually associated with organic aromatic molecules.
