Bis(silylenyl)‐ and Bis(germylenyl)‐Substituted Ferrocenes: Synthesis, Structure, and Catalytic Applications of Bidentate Silicon(II)–Cobalt Complexes

Strong bite: The two respective SiII and GeII centers in ferrocene-containing bis(silylene) and bis(germylene) ligands 1 can serve as excellent σ donors, as shown in the formation of Co complexes 2 (see scheme, Cp=η5-cyclopentadienyl). Unexpectedly, only the bis(silylene)–Co complex 2 is a precatalyst for the [2+2+2] cycloaddition of phenylacetylene and MeCN, possibly because of a stronger coordination of the GeII donor centers to Co.