Vibrational spectra of anhydrous metal pyridine nitrates
Vibrational spectroscopy has been used to investigate the nature of the metal–ligand environment of Cu(py)n(NO3)2 where n= 2, 3, and 4 and M(py)3(NO3)2 where M = Co, Ni, and Zn. Extensive use of isotopic substitution and related techniques were made to assign the low frequency i.r. spectra (350–75 cm–1). It has been observed for the Cu(py)n(NO3)2 system, that as the covalency of the nitrate bonding increases, the copper–oxygen stretching vibration shifts to higher energy, while the copper–nitrogen stretching vibration moves to lower energy.