Silicon complexes with iron carbonyls

Most examples in the literature on hydrosilylation with iron complexes as catalyst concern Fe(CO)5 or related iron carbonyl compounds [41]. The first use of iron pentacarbonyl was reported for the reaction of silicon hydrides with alkenes at 100-140 °C to form saturated and unsaturated silanes according to Scheme 4.20 [42, 43]. 

The reductive elimination process that yields the hydrosilylation product has been recently observed in the decomposition of cis-alkyl (trimethylsilyl)iron carbonyl complexes 133 (212) (eq. [46]). To account for the overall retention of configuration at silicon the hydrosilylation process, the last step should occur with retention. Although not demonstrated, this is very likely, since reductive elimination of hydrosilanes in silyl hydride transition metal complexes occurs with retention of configuration (211,213). 

Unlike the iron triad complexes, cobalt triad compounds, particularly those of Rh and Ir are much more active in hydrosilation catalysis, although the cobalt carbonyl Co2(CO)g has played a very important role in furthering understanding of the catalytic cycle with transition metals. Recently, a simple cobalt salt, CoBr2, in conjunction with added Bu"P, Znl2 and BU4NBH4 was shown to afford 1,4-hydrosilated isoprene (silicon at C-4) in 90% isolated yield, where most metal catalysts derived from Ru, Rh, Pd and Pt usually lead to a mixture of regioisomers. ... 

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