THE TRIAMINES OF COBALT[III]. II. INFRARED AND NUCLEAR MAGNETIC RESONANCE SPECTRA OF SOME AZIDO COMPLEXES

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Abstract
Recent studies(1) have investigated the formation and properties of the geometrical facial and meridional isomers of the triamine complexes of cobalt[III]. While identification of the geometrical isomers of some cobalt[III] complexes with diethylenetriamine [dien] was possible using infrared spectroscopy(2,3), such was not the case with [Co[NH3]3[NO2]3] where proton magnetic resonance spectroscopy provided confirmation of structure. Attention was turned to the azido complexes of cobalt[III] where [Co[NH3]3[N3]3],(4) [Co[dien][N3]3],(5) and [Co[dpt][N3]3](6) [dpt = dipropylenetriamine] have been prepared. Linhard and Weigel reported their preparation of [Co[NH3]3[N3]3] to have meridional geometry based on chemical evidence. In the later two complexes, no structure was reported. This investigation was undertaken to determine if a facial isomer of either triazido-triamminecobalt[III] or triazidodiethylenetriaminecobalt[III] could be prepared. Identification by analysis of the infrared spectra of these complexes is less reliable than other methods because of the relatively small anticipated spectral differences. Also, not much has been reported on the infrared absorptions of coordinated azide ligands(7–12).