Chelate-Ring Formation in Cr (Co)_5(phen) Studied by Laser Frash Photolysis with Visible and Infrared Detection
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Kinetic parameters were obtained for the formation of chelate ring in transient Cr(CO)<SUB>5</SUB>(phen) and 0.17 s<SUP>−1</SUP> (20 °C), ΔH<SUP>‡</SUP> = 85.0 kJ·mol<SUP>−1</SUP>, and ΔS<SUP>‡</SUP> =29.8 J·mol<SUP>−1</SUP>·K<SUP>−1</SUP>, indicating the concerted extrusion of CO by an uncoordinated nitrogen rather than the simple dissociation of CO. In comparison with other bidentate ligands, it was revealed that the structural advantage of phen, which gave significant enhancement in the rate of chelation, was due to entropy term.
- Chemistry Letters
Chemistry Letters 1997(2), 115-116, 1997-02
The Chemical Society of Japan