2,2′-bipyridine- and 1,10-phenanthroline-N-oxide chelates with chromium(III) and iron(III) nitrates[1

Abstract

The syntheses and characterization of Cr(III) and Fe(III) nitrate chelates with 2,2′-bipyridine- and 1,10-phenanthroline-N-oxides(N-bipyO and N-phenO, respectively) are reported. Cr(NO 3) 3 yields chelates of the types [Cr(N-bipyO)(O 2NO) 2] (NO 3) and [Cr(N-phenO) 2(O 2NO)] (NO 3) 2·2C 2H 5OH, involving both N-oxide and nitrato ligands in the complex cations. Lattice ethanol is also present in the latter complex. In the case of Fe(NO 3) 3, both 1:3 and 1:2 complexes with these ligands were obtained. The 1:3 complexes are of the type [FeL 3](NO 3) 3(L = N-bipyO, N-phenO) and are characterized by subnormal, for a high-spin configuration, room temperature magnetic moments, which were attributed to spin-free-spin-paired equilibria, on the basis of studies of magnetic susceptibility variations with temperature. The 1:2 complexes are of the types [Fe(N-bipyO) 2(ONO 2) 2] (NO 3) and [Fe(N-phenO) 2(O 2NO)] (NO 3) 2, the former involving unidentate and the latter bidentate coordinated nitrate. These chelates, as well as the new Cr(III) chelates, are magnetically normal, high-spin compounds.