Structure and reactivity of transition-metal complexes with polyatomic ligands. Part II. Electron spin resonance spectrum and structure of [Cr(CN)5NO]3–

Abstract

Electron spin resonance spectra of dilute fluid and rigid solutions and single crystals of K₃(Co(CN)₆] containing K₃[Cr(CN)₅NO] have been measured, and the principal values of the g and hyperfine tensors derived. It is shown that the anion is axially symmetric and the unpaired electron is primarily in the metal d_xy level. The ¹⁴N anisotropic coupling constant is surprisingly large to be attributed to spin polarisation and indirect dipolar coupling but we cannot discover any reasonable structure which would give a direct delocalisation of the unpaired electron on to the nitrogen atom. In contrast, hyperfine interaction with the equatorial cyanides is small.