Dimeric and monomeric chromium(II) and monomeric chromium(III) aryls. Crystal structure of pyramidal Mz2Cr(py) (Mz = o-Me2NCH2C6H4, py = pyridine), dimeric [(Me2NC6H4)2Cr]2, and octahedral (Me2NC6H4)3Cr

Abstract

Reaction of CrCl2(THF)2 with 2 equiv of [omicron-Me2NCH2C6H4]Li and [omicron-Me2NC6H4]Li led to formation of the monomeric pyramidal [omicron-Me2NCH2C6H4]2Cr(pyridine) (2) and dimeric [(omicron-Me2NC6H4)2Cr]2 (3) with a supershort Cr-Cr contact. Both compounds can be thermolyzed in toluene to form the corresponding monomeric Cr(III) [Me2NC6H4]3Cr (4) and (omicron-Me2NCH2C6H4)3Cr (5) derivatives. The structures of 2-4 have been clarified by X-ray diffraction analysis. Complex 2: triclinic, P1, a = 8.766 (2) angstrom, b = 8.825 (1) angstrom, c = 23.582 (3) angstrom, alpha = 81.41 (1)-degrees, beta = 85.33 (1)-degrees, gamma = 60.31 (1)-degrees, V = 1567.0 (5) angstrom3, Z = 3, R = 0.034 (R(w) = 0.044), T = 130 K for 986 parameters and 6269 significant reflections out of 8191. Complex 3: monoclinic, C2/c, a = 10.563 (3) angstrom, b = 13.563 (2) angstrom, c = 19.813 (8) angstrom, beta = 92.92 (1)-degrees, V = 2835 (1) angstrom3, Z = 4, R = 0.066 (R(w) = 0.092), T = 130 K for 261 parameters and 2583 significant reflections out of 3406. Complex 4: trigonal, P31c a = b = 12.821 (1) angstrom, c = 7.860 (1) angstrom, V = 1118.9 (2) angstrom3, Z = 2, R = 0.060 (R(w) = 0.066), T = 300 K for 92 parameters and 573 significant reflections out of 928.