Synthesis of carbyne complexes of chromium, molybdenum, and tungsten by formal oxide abstraction from acyl ligands

Article abstract of DOI:10.1021/om00148a005

Reaction of the acyl metal complexes [NMe₄][M(C(O)R)(CO)₅] (R = C₆H₅, M = Cr, Mo, W; R = CH₃, M = W) with the Lewis acids COCl₂, C₂O₂Cl₂, C₂O₂Br₂, and ClC(O)OCCl₃ in CH₂Cl₂ at low temperatures (≤-78°C) and subsequent warming of the solutions (≤0°C) lead to clean formation of trans-halo(carbyne)tetracarbonylmetal complexes, [M(CR)(X)(CO)₄] (X = Cl, Br). The carbyne complexes [M(CR)X(CO)₄] are transformed into stabilized derivatives [M(CR)X(CO)₂L₂] by the addition of donor ligands (L₂ = (pyridine)₂ (py), tetramethylethylenediamine (tmeda), bipyridine (bpy)). The complex [W-(CPh)(O₂CCF₃)(CO)₂(tmeda)] is prepared in a similar reaction sequence from [NMe₄][W(C(O)Ph)(CO)₅], (CF₃CO)₂O, and tmeda. Reaction of [NMe₄][W(C(O)Ph)(CO)₅] with C₂O₂Br₂ and 1 equiv of PPh₃ gives [W(CPh)Br(CO)₃(PPh₃)]. The bis(pyridine)-substituted complexes [W(CPh)Cl(CO)₂(py)₂] undergo further substitution reactions with PMe₃ and Ph₂PCH₂CH₂PPh₂ (dppe) to give [W(CPh)Cl(CO)₂(PMe₃)₂] and [W(CPh)Cl(CO)₂(dppe)].