A mixed-valence tri-zinc complex, [LZnZnZnL] (L=bulky amide), bearing a linear chain of two-coordinate zinc atoms

Reduction of a variety of extremely bulky amido Group 12 metal halide complexes, [LMX(THF)0,1] (L=amide; M=Zn, Cd, or Hg; X=halide) with a magnesium(I) dimer gave a homologous series of two-coordinate metal(I) dimers, [L′MML′] (L′=N(Ar†)(SiMe3), Ar†=C6H2{C(H)Ph2}2Pri-2,6,4); and the formally zinc(0) complex, [L*ZnMg(MesNacnac)] (L*=N(Ar*)(SiPri3); Ar*=C6H2{C(H)Ph2}2Me-2,6,4; MesNacnac=[(MesNCMe)2CH]−, Mes=mesityl), which contains the first unsupported Zn[BOND]Mg bond. Two equivalents of [L*ZnMg(MesNacnac)] react with ZnBr2 or ZnBr2(tmeda) to give the mixed valence, two-coordinate, linear tri-zinc complex, [L*ZnIZn0ZnIL*], and the first zinc(I) halide complex, [L*ZnZnBr(tmeda)], respectively. The analogues [L*ZnMZnL*] (M=Cd or Hg), were also prepared, the Cd species contains the first Zn[BOND]Cd bond in a molecular compound. Metal–metal bonding was studied by DFT calculations.