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Thermal Deamination-anation in Cobalt(III) Thiocyanate Complexes. Novel decarbonylation of the equatorial amide ligand

Amirnasr, M. ; Houriet, R. ; Meghdadi, S.

In: Journal of Thermal Analysis and Calorimetry, 2002, vol. 67, no. 3, p. 523-533

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    Titre
    • Thermal Deamination-anation in Cobalt(III) Thiocyanate Complexes. Novel decarbonylation of the equatorial amide ligand
    Auteur
    • Amirnasr, M.. Institute of Physical Chemistry, Swiss Federal Institute of Technology, CH-1015, Lausanne, Switzerland
    • Houriet, R.. Department of Materials Science, Swiss Federal Institute of Technology, CH-1015, Lausanne, Switzerland
    • Meghdadi, S.. Department of Chemistry, Isfahan University of Technology, 84154, Isfahan, Iran
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Journal of Thermal Analysis and Calorimetry, 2002, vol. 67, no. 3, p. 523-533. Kluwer Academic Publishers
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:322432
    Summary
    The solid state thermal behavior of trans-[Co(bpb)(amine)2]NCS⋅H2O complexes where (bpb)=[N,N'-bis(2-pyridinecarboxamido-N)-1,2-benzene], and amine=pyrrolidine (prldn)(1), and benzylamine (bzlan) (2), and trans-[Co(bpb)(piperidine)2]ClO4⋅H2O (3) (mixed with KSCN), has been studied using thermoanalytical techniques, infrared spectroscopy, and pyrolysis coupled to both infrared and mass spectrometry, PY/FTIR and PY/MS. The deamination-anation reaction is clearly observed for all three complexes. The estimated values of E a for the deamination-anation are: E a(1)=246.8 kJ mol−1, E a(2)=255.7 kJ mol−1, E a(3)=234.7 kJmol−1. The trend in E a values is rationalized based on the ligand field strength of the amines and the structural effects. A novel decarbonylation of the amide CO group from the equatorial ligand is observed after the release of one amine molecule. This process has been monitored for complex (1) by FTIR in the carbonyl region and by mass spectrometry for the detection of CO2 at 280°C. The activation energy of this process is estimated for complex (1) (662.5 kJ mol−1). The reaction scheme for the observed reactions is proposed