Rhodium carbonyl complexes containing pyridine carboxylic acid ligands: Reactivity towards various electrophiles and catalytic activity

Dipak Kumar Dutta, Pratap Chutia, Bhaskar J. Sarmah, Bibek J. Borah, Biswajit Deb, J. Derek Woollins

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

The complex [Rh(CO)(2)Cl](2) reacts with two molar equivalent of pyridine carboxylic acids ligands Py-2-COOH(a), Py-3-COOH(b) and Py-4-COOH(c) to yield rhodium(I) dicarbonyl chelate complex [Rh(CO)(2)(L')](1a) {L' = eta(2)-(N,O) coordinated Py-2-COO-(a')} and non-chelate complexes [Rh(CO)(2)CIL''](1b,c) (L'' = eta(1)-(N) coordinated Py-3-COOH(b), Py-4-COOH(c)). The complexes 1 undergo oxidative addition (OA) reactions with different electrophiles such as CH3I, C2H5I, C6H5CH2Cl and I-2 to give penta coordinated Rh(III) complexes of the types [Rh(CO)(CORn)XL'], {n=1,2,3; R-1 =-CH3(2a); R-2 =-C2H5(3a); X=I and R-3 =-CH2C6H5 (4a); X=Cl}, [Rh(CO)I2L'](5a), [Rh(CO)(CORn)ClXL''] {R-1=-CH3(6b,c); R-2 =-C2H5(7b,c); X=I and R-3=-CH2C6H5 (8b,c); X=Cl} and [Rh(CO)ClI2L''](9b,c). The complexes have been characterized by elemental analysis, IR and H-1 NMR spectroscopy. Kinetic data for the reaction of 1a-b with CH3I indicate a first order reaction. The catalytic activity of 1a-c for the carbonylation of methanol to acetic acid and its ester is evaluated and a higher turn over number (TON = 810-1094) is obtained compared with that of the well-known commercial species [Rh(CO)(2)I-2](-) (TON = 653) at mild reaction conditions (temperature 130 +/- 5 degrees C, pressure 35 +/- 5 bar). (C) 2008 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)29-35
Number of pages7
JournalJournal of Molecular Catalysis A: Chemical
Volume300
Issue number1-2
DOIs
Publication statusPublished - 2 Mar 2009

Keywords

  • Rhodium carbonyl complexes
  • Pyridine carboxylic acids
  • Oxidative addition reactions (OA)
  • Carbonylation of methanol
  • OXIDATIVE-ADDITION
  • METHANOL CARBONYLATION
  • CHELATING LIGANDS
  • IRIDIUM
  • <RH2(COME)2(CO)2I6>2
  • DERIVATIVES
  • CHEMISTRY
  • EFFICIENT
  • INSERTION
  • ALCOHOL

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