Metal-ligand stretching, N-O stretching and C-H out-of-plane bending vibrations of pyridine N-oxide and hexakis (pyridine N-oxide) metal perchlorates

Abstract

Infrared spectra of pyridine N-oxide and its metal complexes of the type [M(pyridine N-oxide)6](ClO4)n (MMn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cr3+, Fe3+, Al3+, n = 2 or 3) were observed in the 2000–300 cm−1 region. The metal-ligand stretching and the N-O stretching vibration bands were respectively assigned below 450 cm−1 and at about 1200 cm−1. The CH out-of-plane vibration bands of the free and co-ordinated pyridine N-oxide, appearing in the region 1000–700 cm−1, were assigned by analysis of their combination bands. The frequencies of the metal-ligand stretching, of the N-O stretching and of the CH out-of-plane bending vibrations were found to be closely correlated. The CO stretching frequencies of 3- and 4-acetylpyridine N-oxide and of their metal complexes [M(acetylpyridine N-oxide)6](ClO4)n (MCo2+, Ni2+, Zn2+, Fe3+) were also obtained and are discussed.