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.