Synthesis of a Stable Methylidyne Complex

The successive treatment of [W(CO) 6 ] with LiSiPh 3, (OCBr) 2, and 4-picoline (pic) affords the silylcarbyne complex [W(≡CSiPh 3 )Br(CO) 2 (pic) 2 ], which reacts with 1,2-bis(dicyclohexylphoshino)ethane (dcpe), 1,2-bis(diphenylphosphino)ethane (dppe), and tetramethylethylenediamine (tmeda) to provide the complexes [W(≡CSiPh 3 )Br(CO) 2 (L 2 )] (L 2 = dcpe, dppe, tmeda). Fluoride-mediated protodesilylation of [W(≡CSiPh 3 )Br(CO) 2 (dcpe)] with moist [Bu 4 N]F provides the stable and structurally characterized terminal methylidyne complex [W(≡CH)Br(CO) 2 (dcpe)] (shown) in addition to traces of the ethene-1,2-diylidyne complex {Br(dcpe)(CO) 2 W} 2 (μ-≡CCH═CHC≡).