Hydrosilylation cross-linking of silicon fluids by a novel class of iron(0) catalysts

• Catalytic activity of iron complexes [Fe(CO)3(L)] or [{Fe(CO)3}2L] was examined.
• Fe(0) complexes were proven to exclusively catalyze the formation of unsaturated product.
• Fe(0) complexes appeared to be efficient catalysts of silicone fluids curing process.
• NMR data allowed proposing a scheme of catalysis in molecular and polymeric systems.

Iron(0) carbonyl complexes of the general formula [Fe(CO)3(L)], [{Fe(CO)3}2L] stabilized by multivinylsilicon ligands (where L = diene, triene, tetraene, polyvinyl silicon derivatives) were examined as novel catalysts in the molecular model of cross-linking process as well as various polymeric silicone systems. In the model reactions between vinylheptamethyltrisiloxane and heptamethyltrisiloxane, these complexes proved to be efficient catalysts of dehydrogenative silylation, while in polymeric systems, made of silicone fluids such as poly(vinyl)siloxanes and polyhydrosiloxane, the hydrosilylation was efficiently catalyzed at elevated temperatures. The complexes examined when added to these silicon fluid mixtures proved to be still active after extended storage times, even when exposed to air and moisture. The NMR studies of stoichiometric reactions of [Fe(CO)3{(H2CCHSiMe2)2O}] with molecular substrates as well as the cross-linking catalytic tests in the liquid phase in the presence of these complexes allowed proposing a mechanistic scheme for the catalysis of hydrosilylation vs. dehydrogenative silylation, by the new iron carbonyl catalysts in which [Fe(CO)3] moiety is stabilized by multivinylsilicon derivatives.

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