Rhodium thiolate complexes intercalated in crystalline γ-zirconium phosphate or tethered to SiO2-modified γ-zirconium phosphate have been synthesised. It was observed that the addition of a solution of organic silicates to a colloidal suspension of γ-zirconium phosphate yielded amorphous substrates, which displayed very high specific areas (160–650 m2 g−1). Incorporation of a mercaptocarbonyl rhodium complex resulted in a highly selective and active catalyst precursor for the hydroformylation of 1-heptene in the liquid phase. Elemental analysis and photoelectron spectroscopy of the fresh and used samples revealed that some metal leaching occurs during the reaction, this being mainly confined to the outer layers of the solid particles. This observation, together with the high selectivity towards linear aldehydes, makes SiO2-modified γ-zirconium phosphate a good support candidate for immobilised Rh catalysts. Spectroscopic data obtained from the crystalline precursor and also from the amorphous catalyst showed that the interaction between the rhodium complex and the acid support was achieved [italic v (to differentiate from Times ital nu)]ia hydrogen bonds, forming NH groups.

This research was partly supported by the Interministerial Commission of Science and Technology (CICYT), Spain, under project QUI98-0784. S. M. M. expresses her appreciation to the Ministry of Science and Technology for a contract and S. R. thanks the FEDER programme (Project 1FD97-0176) for a fellowship.