Indenyl Ligands as Supports for Reactive, Low-Valent Cobalt(I) Fragments

Alkali-metal reduction of (η5-C9H5-1,3-(SiMe3)2)2Co (1) in the presence of vinyltrimethylsilane affords the unusual indenyl cobalt(I) dimer 3, where interligand η4-benzo coordination is achieved. Though an aggregate, 3 serves as a ready source of a 14-electron indenyl cobalt(I) equivalent, on the basis of competition experiments between 3 and (η5-C9H5-1,3-(SiMe3)2)Co(COD) (2) with carbon monoxide. The enhanced reactivity of 3 brought about by benzo coordination, relative to a typical donor-ligated source of Co(I), suggests the compound may serve as a promising platform for small-molecule activation and functionalization.