An efficient synthesis of acetylide/trimetal/acetylide molecular wires

Efficient syntheses are reported for incorporating trimetal units of the type M(3)(dpa)(4)(2+) (M = Cr, Co, Ni, and dpa = 2,2'-dipyridylamide) into polyalkynyl assemblies to give the prototypical bis-phenylacetylide complexes M(3)(dpa)(4)(CCPh)(2). Reactions of M(3)(dpa)(4)Cl(2) with LiCCPh have led only to mixtures of products which cocrystallize forming materials of the composition M(3)(dpa)(4)(CCPh)(x)()Cl(2)(-)(x)(). Here we report that acetonitrile complexes [M(3)(dpa)(4)(NCCH(3))(2)](PF(6))(2) react cleanly with LiCCPh in MeCN to afford the desired target molecules in 40-60% yield and in excellent purity. Isolation of the mixed ligand complex [Co(3)(dpa)(4)(NCCH(3))(CCPh)]PF(6) has been accomplished, which suggests that these reactions are stepwise and that it will be possible to synthesize mixed acetylide complexes (i.e., M(3)(dpa)(4)(CCR)(CCR')) via this method.