Crystal structure and E.S.R. of 2,2'-Bipyridylium Tris(2,2'-bipyridyl)iron(III) tetraperchlorate

Abstract

The crystal structure of the title compound (C10H9N2) [Fe(C10H8N2)3] (ClO4)4 has been determined at c. 295 K from diffractometer data and refined by least squares to R 0.056 (7018 reflections with I > 3σ(I)). Crystals are triclinic, Pī, a 16.607(3), b 13.496(3), c 10.254(2) Ǻ, α 101.13(2), β 92.08(2), γ 102.77(1)°, Z 2. The iron atom is surrounded by three bidentate ligands, the six Fe-N distances being equal (<Fe-N> 1.963 Ǻ). The monoprotonated bipyridylium cation adopts the unusual cis configuration, with the proton clearly located on one of the nitrogen atoms. The e.s.r. g-tensor is approximately axial (g|| 1.474, g, 2.690) but its axes do not coincide with obvious geometric features of the cation.