Interaction of cyanide with iron(II) phthalocyanine: kinetics and equilibria

Abstract

The kinetics and equilibria for the reaction between cyanide and iron(II) phthalocyanine [Fe(pc)](H₂pc = phthalocyanine) in dimethyl sulfoxide (dmso) were studied at 25 °C. The complex [Fe(pc)(CN)₂]^2– is formed in two consecutive pseudo-first-order processes with k_2f= 17.5 ± 0.8 dm³ mol^–1 s^–1 and k_3f= 0.20 ± 0.05 dm³ mol^–1 s^–1, where k_2f and k_3f are the rate constants for the binding of the first and second cyanide ligands, respectively. The equilbrium constants were fund to be K₂= 3.0 × 10³ dm³ mol^–1 and K₃= 5.7 × 10² dm³ mol^–1, for the formation of [Fe(pc)(CN)(dmso)]^– and [Fe(pc)(CN)₂]^2–, respectively.