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      https://www.ias.ac.in/article/fulltext/jcsc/109/04/0235-0248

    • Keywords

       

      Schiff base complex; chromium(III) complex; ligand substitution reactions; structure reactivity correlation

    • Abstract

       

      Complexes of general formulation [Cr(Schiff-base)(H2O)2]X, where Schiff-base=1, 2-bis(salicylideneamino)ethane (salen), 1, 3-bis(salicylideneamino) propane (salprn) and 1, 4-bis(salicylideneamino)butane (salbuen) and X=ClO4 or Cl have been prepared and characterised. Single-crystal structure of the complexrans[Cr(salprn)(H2O)2]Cl has been resolved. Evidence for less distorted coordination geometry around chromium in the salprn analogue as compared to that intrans-[Cr(salen)(H2O)2]+ has been presented. The kinetics of the aqua ligand substitution in the complexes Cr(Schiff-base)(H2O)2+ by thiocyanate have been investigated under pseudo-first order conditions with [NCS]≫[Cr(III)],T=10–50°C, [H+]=10−8−10−1 M,I=1.0M (LiClO4). An attempt has been made to discuss the anomalous lability oftrans-[Cr(salen)(H2O)2]+ reported earlier in comparison to the reactivities of salprn and salbuen analogues. Bimolecular rate constants for the aqua ligand substitution by NCS in [Cr(Schiff-base)(H2O)2]+ at 25°C vary by more than two orders of magnitude depending on the nature of the Schiff-base ligand. The reactivity order is discussed in terms of the possible steric strain imposed by the equatorially coordinated quadridentate ligand.

    • Author Affiliations

       

      M Kanthimathi1 Balachandran Unni Nair1 T Ramasami1 T Shibahara2 T Tada3

      1. Central Leather Research Institute, Adyar, Madras - 600 020, India
      2. Department of Chemistry, Okayama University of Science, 1-1 Ridai-cho, Okayama - 700, Japan
      3. Analytical Research Laboratory, Fujisawa Pharmaceutical Company Ltd., 2-1-6 Kashima, Yodogawa-Ku, Osaka - 532, Japan
    • Dates

       
  • Journal of Chemical Sciences | News

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