Polymer-immobilized Rh(I) complexes were prepared by the reaction of poly (4-vinylpyridine) (PVPy), poly (1-methyl-4-vinylpyridiumiodide) (PVPyMe^+I^-) and copoly (4-vinylpyridine/1-methyl-4-vinylpyridium iodide) [P(VPy-VPyMe^+I^-) with Rh2 (CO)4Cl2, and their catalytic behaviors for the carbonylation of methanol to acetic aicd with CH3I as unique promotor was investigated. The IR studies of these catalysts indicated that the different active species produced by means of different bonding states between Rh(I) complex ions and functional groups in the above polymeric chains demonstrated a remarkable influence on the catalytic reactivities. The chelate-type catalyst with the double coordinations of two free base pyridine ligand groups to cis-dicarbonylrhodium, Rh(I)/PVPy, exhibited apparently a lower catalytic reactivity, while the ionically bound catalyst Rh(I)/PVPyMe^+I^- and the heterobound catalyst Rh(I)/P(VPy-VPyMe^+I^-) wre revealed to be of higher catalytic activities and selectivities under the same reaction conditions, in particular, the catalyst Rh(I)/P(VPy-VPyMe^+I^-) had the best rate enhancement for the catalytic carbonylation because of the formation of a five-coordinate intermediate which had a better nucleophilicity towards methyl iodide, and was found to be more active and favorable to the oxidative addition of the later.

Key words: PYRIDINE P, CATALYST, METHANOL, ACETIC ACID, RHODIUM, CARBONYLATION, CATALYTIC BEHAVIOUR