Theoretical Investigation of the Mechanism of Methanol Carbonylation Catalyzed by Dicarbonyldiiodorhodium Complex
E. A. Ivanova,1 V. A. Nasluzov,1 A. I. Rubaylo1and N. Rösch2
1Institute of Chemistry and Chemical Technology, Siberian Branch of the Russian Academy of Sciences,
Ul. K. Marxa 42, Krasnoyarsk 660049 (Russia),
E-mail: ei@krsk.info
2Institut fur Physikalische und Theoretische Chemie, Technische Universitat Munchen,
85747 Garching (Germany), E-mail: roesch@ch.tum.de
Страницы: 101-108
Аннотация
The entire potential energy profile of the catalytic cycle of methanol carbonylation catalyzed by [Rh(CO)2I2]– complex was explored computationally using a gradient-corrected density functional method and polarizable continuum model for accounting of solvent effects. For this purpose, the relative energies of the intermediates and transition states for CH3I oxidative addition, the CO migratory insertion and the CH3COI reductive elimination were estimated. Based on calculated energies the lowest-energy reaction path was deduced to be determined by the cis-dicarbonyl species in spite the trans-conformers of 6-coordinated intermediates [RhCH3(CO)2I3]– and [Rh(CH3CO)(CO)2I3]– were found to be more stable. The explanation is the lower activation barriers for transformation of cis-conformers to products. The activation barriers for oxidative addition, CO migratory insertion and reductive elimination steps were calculated to be at 135, 40 and 75 kJ/mol, respectively. The first step was found to be the rate-determining. The accounting for solvent effects makes the energy profile smoother and more consistent with experimental reaction profile.
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