Synthesis, solid state structures and EPR studies in polycrystalline and single crystal samples of -diimine cobalt(II) complexes

V. ROSA; P. J. GONZALEZ; T. AVILÉS; P. T. GOMES; R. WELTER; A. C. RIZZI; M. C. G. PASSEGGI; C. D. BRONDINO

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

Wiley-VCH Verlag GMBH

Año: 2006 p. 4761 - 4769

1434-1948

Cobalt compounds of the general formula [CoX2(α-diimine)],where X = Cl or I and the α-diimines are 1,4-diaryl-2,3-dimethyl-1,4-diaza-1,3-butadiene (Ar-DAB) and bis(aryl)-acenaphthenequinonediimine (Ar-BIAN) were synthesizedby the direct reaction of the anhydrous cobalt salts CoCl2 or CoI2 and the corresponding α-diimine ligand in dried CH2Cl2. The synthesized compounds are [Co(Ph-DAB)Cl2] (1a), [Co(o,o,p-Me3C6H2-DAB)Cl2] (1b), and [Co(o,o-iPr2C6H3-DAB)Cl2] (1c) with the ligands Ar-DAB, and also [Co(o,o,p-Me3C6H2-BIAN)I2] (2b) with the ligand Ar-BIAN. The crystal structures of all the compounds were solved by single-crystal X-ray diffraction. In all cases the cobalt atom is in a distorted tetrahedron, which is built up of two halide atoms and two nitrogen atoms of the α-diimine ligand. Xband EPR measurements of polycrystalline samples performedon compounds 1b, 1c, and 2b indicate a high-spinCoII ion (S = 3/2) in an axially distorted environment. Singlecrystal EPR experiments on compounds 1b and 1c allowed us to evaluate the orientation of the g tensor in the molecular frame.