Two triphenylphosphine analogs, (4-tert-butylphenyl)diphenylphosphine (1) and bis-(4-tert-butylphenyl)phenylphosphine (2), have been synthesized for the preparation of Rh-P complexes with a formula of Rh(CO)Cl(L)(2) (L stands for the ligands 1 and 2, respectively). Such Rh-P complexes were then attached to amino-group functionalized MCM-41 and MCM-48 for the hydroformylation of 1-hexene in the liquid phase. The supports and the heterogeneous catalysts were characterized by means of XRD, nitrogen adsorption-desorption, FT-IR, HRTEM and AAS. The heterogenized catalysts showed catalytic activity and normal heptanal selectivity comparable to the corresponding homogeneous ones; the advantage in the product selectivity towards the normal heptanal due to the larger cone angle of the ligands over Rh-PPh3 in the homogeneous systems was also observed in the heterogeneous ones. Considerable interactions occurred between the surface amino-groups and the active rhodium species during the immobilization, resulting in highly dispersed active Rh-moieties and a significant modification in the catalytic stability. (C) 2004 Elsevier B.V. All rights reserved.