Transition-metal complexes of the 2,3-dipyridylquinoxalines. Part III. Cobalt(II), nickel(II), and copper(II) halide derivatives of 6-methyl-2,3-di-(2-pyridyl)quinoxaline and 6,7-dimethyl-2,3-di-(2-pyridyl)quinoxaline

Abstract

The cobalt(II), nickel(II), and copper(II) halide complexes of 6-methyl-2,3-di-(2-pyridyl)quinoxaline (dpmq) and 6,7-dimethyl-2,3-di-(2-pyridyl)quinoxaline (dpdmq) are described, and the structures interpreted on the basis of magnetic and spectral data. For cobalt, the octahedral complexes CoX₂L (L = dpmq, X = Cl, Br; L = dpdmq, X = Br, l) and the tetrahedral complexes Col₂(dpmq) and CoCl₂(dpdmq) were isolated. The nickel complexes, NiX₂L (L = dpmq, X = Cl, Br, l; L = dpdmq, X = Cl, Br) and Nil₂(dpdmq)(H₂O)₂ have octahedral geometries. All the Cu^II complexes have the stoicheiometry CuX₂L, but three different geometries are apparent. CuCl₂(dpmq) and CuBr₂(dpdmq) are distorted octahedral, CuBr₂(dpmq) has a square planar structure, and CuCl₂(dpdmq) is believed to be distorted tetrahedral.