Transition-metal complexes of the 2,3-dipyridylquinoxalines. Part IV. Cobalt(II), nickel(II), and copper(II) halide derivatives of 6-methyl-2,3-di-(6-methyl-2-pyridyl)quinoxaline and 6,7-dimethyl-2,3-di-(6-methyl-2-pyridyl)quinoxaline
Abstract
The cobalt(II), nickel(II), and copper(II) halide complexes of 6-methyl-2,3-di-(6-methyl-2-pyridyl)quinoxaline (dpq) and 6,7-dimethyl-2,3-di-(6-methyl-2-pyridyl)quinoxaline (dmpq) are described, and the structures are interpreted on the basis of magnetic and spectral data. For cobalt and nickel, the complexes MX2(dpq)(M = Co, Ni; X = Cl, Br, I) and MX2(dmpq)(M = Co; X = Cl, Br, I; M = Ni; X = Br, I) were isolated and shown to be essentially tetrahedral. NiCl2(dmpq), which has a distorted octahedral structure, was also isolated. The complexes CuCl2(dpq) and Cu2Cl4(dmpq) have square planar structures, but the data for CuBr2(dpq) do not allow conclusive structural assignments to be made. The solution properties of the complexes are described and interpreted.