How long are Ga⇆Ga double bonds and Ga–Ga single bonds in dicationic gallium dimers?

Abstract

Syntheses and characterization of two salts [(L)GaGa(L)][pf]₂ ([pf]⁻ = [Al(OR^F)₄]⁻; R^F = C(CF₃)₃) are reported. They include the first dicationic digallene [(L)Ga⇆Ga(L)]²⁺ (L = CDP^Ph = C(PPh₃)₂) and a digallane [(L)Ga–Ga(L)]²⁺ (L = [NacNac^Mes]⁻). The CDP^Ph-supported digallene dication includes a trans-bent [L–GaGa–L]²⁺ bond that is analogous to neutral R–GaGa–R molecules and related to Robinson's famous “Digallyne” [R–GaGa–R]²⁻. The dicationic digallane [(L)Ga–Ga(L)]²⁺ is analogous to the widely used “Jones magnesium dimer”, but includes a very short Ga^II–Ga^II single bond.