Dutta, D K and Deb, B and Hua, G and Woollins, J D
(2012)
Chelate and trans effect of P,O donor phosphine ligands on rhodium catalyzed
carbonylation of methanol.
Journal of Molecular Catalysis A: Chemical, 353-54.
pp. 7-12.
ISSN 1381-1169
Abstract
Four complexes of the type [Rh(CO)Cl(�2-P,O-L)](1a,1b) and [Rh(CO)Cl(�1-P-L)2](2a,2b), where
L = Ph2PC6H4-2-OCH3(a) and Ph2PC6H4-2-CH2OCH3(b), have been synthesized by the reaction of
[Rh(CO)2Cl]2 with appropriate mol equivalents of the ligands in CH2Cl2. The complexes show single
intense �(CO) bands in the range 1965–1989 cm−1 indicating the presence of terminal carbonyl groups.
All the complexes have been characterized by elemental analyses, mass spectrometry, IR and multinuclear
NMR (1H, 31P and 13C) spectroscopy, and the molecular structure of the ligand b is determined by
single crystal X-ray diffraction. The complexes undergo oxidative addition (OA) with excess CH3I to afford
Rh(III)-acyl complexes of the type [RhCl(COCH3)I(L)](3a,3b) and [RhCl(COCH3)I(L)2](4a,4b). The kinetic
data for the OA reactions with CH3I indicate a first order reaction and also exhibit that the rate of OA
for the chelate complexes (1a and 1b) is higher than those of trans-complexes (2a and 2b). The catalytic
efficiencies of 1a, 1b, 2a and 2b in carbonylation of methanol exhibit higher Turn Over Frequency (TOF)
689–1808 h−1 than the well-known Monsanto’s species [Rh(CO)2I2]− (TOF = 464–1000 h−1) under similar
experimental conditions. The catalytic activities vary in the order as 1a > 1b > 2a > 2b
Actions (login required)
 |
View Item |
![[img]](http://neist.csircentral.net/style/images/fileicons/application_pdf.png)
