Spectroscopic monitoring of carbonylation reactions on zeolite supported rhodium(I) carbonyls

• Rh(CH3COCHCOCH3)(CO)2 was anchored onto HY zeolite.
• ATR FTIR spectra showed [Rh(CH3COCHCOCH3)(CO)2] anchored onto HY zeolite by losing [CH3COCHCOCH3]− ligand.
• Oxidative addition of methyl iodide to form Rh(III) and reductive elimination of CO to for Rh(I) were evaluated.
• Observed rate constants determined from ATR FTIR and XPS were mutually consistent with each other.

A rhodium(I) dicarbonyl on HY zeolite prepared from [Rh(CH3COCHCOCH3)(CO)2] were charaterised by Attenuated Total Reflectance Fourier Transformed Infrared (ATR FTIR) and X-ray Photoelectron Spectroscopy (XPS). The ATR FTIR spectra of the anchored rhodium complex showed that [Rh(CH3COCHCOCH3)(CO)2] reacted with the HY zeolite by loosing the [CH3COCHCOCH3]− ligand to form Rh(CO)2/HY zeolite and [CH3COCHCOCH3]/HY zeolite. The sharpness of the v(CO) bands measured by the ATR FTIR showed that the rhodium(I) dicarbonyl complex are distributed fairly uniform over the zeolite support. This heterogeneous catalyst was monitored for the oxidative addition of methyl iodide in the liquid phase, followed by reductive elimination of acetyl iodide upon treatment with CO gas.These reactions were monitored by following the carbonyl stretching frequencies from ATR FTIR measurements and the change in binding energy of the Rh 3d5/2 photoelectron line as measured by XPS, observed rate constants determined were mutually consistent with each other.

Rh(CO)2/HY zeolite was prepared from [Rh(CH3COCHCOCH3)(CO)2]. The ATR FTIR spectra showed that [Rh(CH3COCHCOCH3)(CO)2] reacted with the support by loosing the [CH3COCHCOCH3]− ligand. The sharpness of the v(CO) bands is an indication of the fairly uniform distribution of the rhodium(I) dicarbonyl complex on the zeolite support. This catalyst was tested for the oxidative addition of methyl iodide, followed by reductive elimination of acetyl iodide upon treatment with CO gas. This reaction was followed by ATR FTIR and by XPS.Figure optionsDownload as PowerPoint slide