A periodic mesoporous organosilica containing a carbapalladacycle complex as heterogeneous catalyst for Suzuki cross-coupling

A series of periodic mesoporous organosilica with varying contents of a carbapalladacycle complex forming part of the walls of the hybrid material has been prepared. These solids have a very large surface area (ca. 1000 m(2) g(-1)), a mononodal pore size distribution (ca. 3 nm), and a periodic hexagonal structure typical for MCM-41 materials. The fresh solids exhibit high activity for the Suzuki cross-coupling of phenylboronic acid with bromobenzoic acid and bromoacetophenone. The initial catalytic activity of these PMO materials is significantly higher than that of a related amorphous silica catalyst containing the same complex. Leaching studies, either filtering the solid in hot solution or three-phase-test attaching one of the reagents to a solid, demonstrate that there is a contribution to the catalysis of leached species from the solid into the solution. The solid can be reused although a progressive deactivation caused by complex degradation, and mesopore collapse has been observed. (C) 2004 Elsevier Inc. All rights reserved.