A mechanistic study of thermal C-H reductive elimination from a six-coordinate d6 indium complex

Glen P. Rosini, Kun Wang, Bhushan Patel, Alan S Goldman

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Abstract

The thermolysis of trans-IrL2(CO)Cl(H)(C6H5) (1a; L=P(i-Pr)3; H trans to CO) produces benzene and the Vaska-type complex IrL2(CO)Cl. A mechanistic study of the reaction has shown that 1a reversibly loses CO at 120 °C (as evidenced by the incorporation of 13CO) and isomerizes to the previously unreported 1b (H trans to Cl). It was found that 1b is the complex primarily responsible for the formation of benzene upon thermolysis under CO atmosphere; direct loss of benzene from 1a was determined to be, at most, a minor pathway. Benzaldehyde was also formed as a product of thermolysis of 1a under CO atmosphere. The first-order rate constant for benzene elimination in the absence of CO was found to be 8.5×10-5 s-1. The presence of only 5 Torr CO results in a decrease to 2.0×10-5 s-1, but little further inhibition is observed above 5 Torr CO. Added dihydrogen (100 Torr) was found to effect a novel catalysis of benzene elimination from 1a in the absence of CO atmosphere; it is suggested that trace amounts of dihydrogen, present in solutions of 1a, are responsible for the enhanced rate of elimination in the absence of CO. The thermolysis of 1-d6 in toluene was found to proceed without any toluene incorporation, implying that arene loss is irreversible.

Original languageEnglish
Pages (from-to)537-542
Number of pages6
JournalInorganica Chimica Acta
Volume270
Issue number1-2
Publication statusPublished - Apr 2 1998

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Keywords

  • Aryl complexes
  • Hydride complexes
  • Iridium complexes
  • Reductive elimination
  • Six-coordinate complexes
  • Thermolysis

ASJC Scopus subject areas

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

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