Organic–inorganic hybrid materials containing metal phosphine complexes: Evidence for preferential cis configuration of Pd(II) and Pt(II) complexes within the materials

The hydrolysis–polycondensation of palladium (Pd) and platinum (Pt) complexes of phosphines [p-(OiPr)3SiC6H4]2PC6H5 and [p-(OiPr)3SiC6H4]3P gives rise to xerogels in which the metal complexes are included within a silica matrix with retention of the arrangement around the metal centre. However, the trans-Pd as well as the trans-Pt complexes incorporated within the xerogels slowly isomerize into the more stable cis complexes. Direct reaction of (CH3CN)2PdCl2 with xerogels prepared from both phosphines leads to the incorporation of the Pd salt, the corresponding complexes always adopting a cis arrangement of the ligands. Treatment with nBu3P of all the materials containing metal centres leads to the complete removal of the metal except for the materials obtained by hydrolysis of the metal–[p-(OiPr)3SiC6H4]3P complexes.