A [CoSiH] Silylene Synthon Provides Modular Access to Homo- and Heterobimetallic [Co═Si═M] (M = Co, Fe) Silicide Complexes.

Base-stabilized BPCoSiH(DMAP) (, [BP] = PhB(CHPPr); DMAP = 4-dimethylaminopyridine) is a rare instance of a synthon for the simplest "parent" silylene complex (LM═SiH). Complex was accessed in high yields via double Si-H bond activation in SiH by [BP]Co(DMAP), and in solution, it undergoes rapid exchange between bound and free DMAP by an associative mechanism (as determined by variable-temperature H NMR dynamic studies). The DMAP ligand of is readily displaced by metal-based fragments that bind silicon and cleave the Si-H bonds of the SiH moiety to produce bimetallic [Co═Si═M] (M = Co, Fe) molecular silicides. Thus, treatment of with 0.5 equiv of (LCo)(μ-N) (L = a tripodal ligand) resulted in the spontaneous formation of BPCo═Si═Co(H)L (L = [BPPz], PhB(CHPBu)(pyrazolyl) (); Tp″, HB(3,5-diisopropylpyrazolyl) ()) with the concomitant release of DMAP. The symmetrical silicide BPCo═Si═Co(H)[BP] () was prepared by treatment of a mixture of and [BP]Co(DMAP) with 2 equiv of PhB, which in this case is required to sequester DMAP as the elimination product PhB-DMAP. A heterobimetallic silicide, BPCo═Si═Fe(H)[SiP] (; [SiP] = PhSi(CHPPr)), was obtained via KC reduction of [SiP]FeCl and subsequent addition of and PhB. These transformations involving a metal-SiH derivative demonstrate a fundamentally new type of reactivity for silylene complexes and provide a unique synthetic method for construction of molecular silicide complexes.