Dedicated to the memory of Professor Michel CheNi II and Mn III Schiff base complexes (Salophen-Ni and Salophen-MnCl) bearing a pending carboxylic group were prepared and characterized. Both complexes were grafted onto a mesoporous amino-functionalized SBA-15 silica, by formation of an amide function between the propylamine groups of the support and the carboxylic acid functions of the salophen ligand (corresponding respective to 1.30 wt.% of Ni and 1.06 wt.% of Mn). The co-catalytic behaviour of the free and grafted complexes was then evaluated in the CO 2 cycloaddition reaction onto styrene oxide, using tetra-butylammonium bromide ( nÀ Bu 4 NBr) as the main catalyst. In homogeneous conditions, the Mn III Schiff base complex and the Ni II one, to a lesser extent, behave as efficient co-catalysts for this reaction (styrene conversion of 100 % and 65 % respectively after 3 h at 120°C, under 15 bars of CO 2 ). Upon immobilization at the surface of the aminofunctionalized SBA-15, we showed that the co-catalytic activity of the less efficient one, i. e. Ni 2 + salophen complex, could be enhanced (reaching a full conversion after 7 h), hence highlighting a potential synergistic effect between the unused amine functions of the support and the Ni 2 + salophen cocatalyst. Both salophen complexes were successfully re-used in homogeneous conditions or after their immobilization without any appreciable loss of activity. This work is only a first step towards a completely heterogeneous catalytic system, in which the tetraalkylammonium halide catalyst and the metal-salophen co-catalyst will both be covalently anchored on the same support.

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