Electron spin resonance study of the complex ions [Fe(NO2)(CN)5]5? and [Fe(CN)5NO]3?
- 1 January 1970
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 339-341
- https://doi.org/10.1039/j19700000339
Abstract
A complex ion thought to be [Fe(NO2)(CN)5]5– has been prepared by reduction of [Fe(NO2)(CN)5]4– with sodium borohydride. The e.s.r. spectrum has gx 1·9993, gy 1·9282, and gz 2·0080, and Ax(14N)–32G, Ay 10G, and Az 15G. These parameters are in agreement with expectation for the ion if the unpaired electron is in an orbital of b1 symmetry, being about 75% localised on the NO2 ligand, which thus resembles NO2 2–. This is the same species as that detected after reduction of sodium nitroprusside by aqueous sodium sulphide. The equilibrium [Fe(CN)5NO]3–+ 20H–⇌[Fe(NO2)(CN)5]5–+ H2O is invoked to explain the effect of pH on the system. This contrasts with the conclusion of van Voorst and Hemmerich who postulated an equilibrium of the form [Fe(CN)5NOH]2–+ OH–⇌[Fe(CN)5NO]3–+ H2O.Keywords
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