Equilibrium and kinetic study of piperidine binding to phthalocyaninatoiron(II) in dimethyl sulfoxide

Paolo Ascenzi, Claudio Ercolani, Fabrizio Monacelli

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The reaction between piperidine (Pip) and phthalocyaninatoiron(II) ([Fe(pc)]) in dimethyl sulfoxide (dmso) has been studied at 20.0 °C, from both equilibrium and kinetic viewpoints. In excess of Pip, the adduct [Fe(pc)(Pip)2] is formed via two consecutive pseudo-first-order processes. The observed rate constants have the general form: kobs=k1f[Pip] +k1r with k1f′ = (8.7 ± 0.2) × 103 dm3 mol-1 s-1 and k1f″ = (8.3 ± 0.2) × 101 dm3 mol-1 s-1, for the binding of the first and second Pip molecule, respectively. Equilibrium experiments yield K1′ = (1.0 ± 0.1) × 105 dm3 mol-1 and K1″ = (1.3 ± 0.1) × 103 dm3 mol-1 for the stepwise formation of the [Fe(pc)(dmso)(Pip)] and [Fe(pc)(Pip)2] adducts, respectively. From the values of the second-order rate constants (k1f′ and k1f″) and of the equilibrium constants (K1′ and K1″), the dissociation rate constants have been estimated to be k1r′= (8.7 ± 1) × 10-2 s-1 and k1r″ = (6.4 ± 0.7) × 10-2 s-1. Present results are discussed in the light of related previous studies.

Original languageEnglish
Pages (from-to)199-203
Number of pages5
JournalInorganica Chimica Acta
Issue number1-2
Publication statusPublished - 1994


  • Amine complexes
  • Iron complexes
  • Kinetics and mechanism
  • Phthalocyanine complexes
  • Piperidine binding
  • Thermodynamics

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry


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