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}2Pr(i)-2,6,4); and the formally zinc(0) complex, [L*ZnMg((Mes)Nacnac)] (L*=N(Ar*)(SiPr(i)3); Ar*=C6H2{C(H)Ph2}2Me-2,6,4; (Mes)Nacnac=[(MesNCMe)2CH](-), Mes=mesityl), which contains the first unsupported Zn-Mg bond. Two equivalents of [L*ZnMg((Mes)Nacnac)] react with ZnBr2 or ZnBr2(tmeda) to give the mixed valence, two-coordinate, linear tri-zinc complex, [L*Zn(I)Zn(0)Zn(I)L*], 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-Cd bond in a molecular compound. Metal-metal bonding was studied by DFT calculations.