Preparation and properties of trisodium pentacyano(isonicotinohydrazide)ferrate(II) hexahydrate and the kinetics of its substitution reactions

Abstract

The preparation, spectral properties (visible, i.r., and n.m.r.), and conductivity of the title complex Na3[Fe(CN)5(inh)]·6H2O, containing isonicotinohydrazide bound through the pyridine nitrogen atoms, are described. The rate of formation of [Fe(CN)5(inh)]3– from [Fe(CN)5(OH2)]3– and inh in aqueous solution at 25 °C is 3.25 × 102 dm3 mol–1 s–1 and the rate of release of inh from the complex is 7.3 × 10–4 s–1, with ΔH‡= 108 kJ mol–1 and ΔS‡= 59.8 J K–1 mol–1. These parameters are very close to values reported for the corresponding isonicotinamide complex.