Mixed-ligand complex formation in the copper(I)-2,9-dimethyl-1,10-phenanthroline-3,3′-bridged biquinoline system as probed by 1H NMR

The interaction of the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline (neocuproine, DMP) with 2,3,8,9-dibenzo-4,7-dimethyl-5,6-dihydro-1,10-phenanthroline (cuprotest, DMQ) in a CD₃OD solution has been studied by ¹H NMR. DMQ is substituted for the DMP ligand in the inner coordination sphere of the Cu⁺ complex. To describe the experimental integrated intensities of NMR signals as a function of concentrations of the components, a model of the process is proposed implying the formation of a heteroleptic complex, which, presumably, has a bridging structure.