4-Ethoxypyridine N-oxide complexes of metal halides and perchlorates

Abstract

Complexes of 4-ethoxypyridine N-oxide (EPNO) with metal halides and perchlorates were synthesized and characterized by means of spectral, magnetic, conductance and, in certain cases, X-ray powder diffraction studies. Mn(EPNO)Cl 2 and Pd(EPNO) 2Cl 2 are the first examples of pyridine N-oxide complexes of this type for these metal ions. Co(EPNO) 2Cl 2 shows differences in its solution spectra from analogous complexes of other substituted pyridine N-oxides. Although some metal perchlorates form analogous cationic complexes to those reported for pyridine N-oxides, those of Mn II, Co II, Ni II and Zn II form pentacoordinated cationic complexes, of the type [M(EPNO 5](ClO 4) 2. The Mn II, Co II and Ni II perchlorate complexes are of the high-spin type. The presence of both penta- and hexa-coordinated species in equilibrium in solutions of the Co II and Ni II perchlorate complexes containing excess free ligand has been established by means of spectral evidence. Satisfactory correlation of the NO stretching vibration of EPNO and some of its metal complexes with the ν NO of other 4-substituted pyridine N-oxides and their correspondig complexes has been observed in ν NO vs. σ + plots.