Isotopic Studies of the Metal–Ligand Bond. Part II. The Far Infrared Spectra of Some Binuclear and Polymeric Copper Carboxylate Derivatives; Variable Temperature and Isotopic Studies of the Copper–Ligand Vibrations

The far infrared spectra of 16 adducts of pyridine, quinoline, isoquinoline, urea, aniline, o- and p-toluidine with copper acetate, propionate, and butyrate, and of copper formate tetrahydrate were recorded at ambient temperature and at −196 °C. A range of derivatives were prepared containing isotopically pure 65Cu. The spectra of these derivatives were used to identify, unequivocally, the copper–oxygen stretching frequencies.Complexes believed to be polymeric (aniline and toluidine adducts) exhibit one copper–oxygen stretching vibration between 300 and 350 cm−1 A second band, lying between 350 and 400 cm−1 is not isotopically sensitive. The dimeric complexes exhibit one or two bands in the 300–400 cm−1 region, all of which are isotopically sensitive. Certain of the amine adducts exhibit an isotopically sensitive band near 240 cm−1 assignable to a Cu—N stretching mode.