Aminocarbyne coupling reactions at M(Ph2PCH2CH2PPh2)2(M = Mo or W) sites. Synthesis and properties of the diaminoacetylene complexes trans-[MX(η2-MeHNCCNHMe)-(Ph2PCH2CH2PPh2)2]A (X = F, Cl or ClO4; A = BF4′PF6′HCl2or ClO4) and of their di(aminocarbyne)-type precursors

Abstract

Treatment of trans-[M(CNMe)2(dppe)2]1(M = Mo or W, dppe = Ph2PCH2CH2PPh2) in CH2Cl2 with HA (A = BF4′ PF6′ Cl or ClO4) gives the diaminoacetylene complexes trans-[MX(η2-MeHNCCNHMe)(dppe)2]A 2(X = F, Cl or ClO4; A = BF4′ PF6′ HCl2 or ClO4). The crystal structure of trans-[MoF(η2-MeHNCCNHMe)(dppe)2][BF4] has been determined. A key intermediate in the reaction, trans-[M(CNHMe)2(dppe)2]A23(A = HCl2 or ClO4), has also been isolated and shown to be best viewed as a ‘iminomethylenium’ species CNHMe. The acetylenic CC triple bond in 2 undergoes base-induced cleavage (e.g., by LiBun) to form the parent complex 1.