Synthesis and characterization of ferrocenyl-modified mesoporous silicates

The mesoporous silicates MCM-41 and FSM-16 have been functionalized with a range of ferrocenyl groups. The general synthetic methodology involves either reaction of the strained [1]ferrocenophanes [Fe(eta-C5R4)(2)SiMe2] (R = H or Me), [Fe(eta-C9Me6)(eta-C5H4)SiMe2], or the ferrocenyl carbocation [Fe(eta-C5Me5)(eta-C5Me4CH2)](+) with the dehydrated mesoporous silicate. The materials have been extensively characterized by (inter alia) solid-state C-13 and Si-29 NMR and Fe K-edge EXAFS spectroscopy. The reaction of either [Fe(eta-C5H4)(2)SiMe2] or [Fe(eta-C5Me4)(2)SiMe2] with MCM-41 affords both single ferrocenyl and short chain oligo(ferrocenyl) units grafted to the silicate walls of the mesopores. In contrast, the reaction of [Fe(eta-C-9-Me-5)(eta-C5H4)SiMe2] with MCM-41 gives only a single type of ferrocenyl group attached to the pore walls via a regiospecific ring-opening reaction in which the Si-(C5H4) bond is broken in preference to the Si-(C9Me6) bond.