Annulated carbocyclic gallylene and bis-gallylene with two-coordinated Ga(i) atoms.

The first carbocyclic gallylene [(ADC)Ga(GaI)] and bis-gallylene [(ADC)Ga] (ADC = PhC{N(Dipp)C}; Dipp = 2,6-iPrCH) featuring a central CGa ring annulated between two 1,3-imidazole rings are prepared by KC reductions of [(ADC)GaI]. Treatment of [(ADC)Ga] with Fe(CO) affords complex [(ADC)GaFe(CO)] in which each Ga(i) atom serves as a two-electron donor. [(ADC)Ga] activates white phosphorus (P) and the C -F bond of aryl fluorides (ArF) to yield compounds [(ADC)Ga(P)] and -/-[(ADC)GaF(Ar)], respectively. [(ADC)Ga] undergoes oxidation with (MeS)AuCl to give [(ADC)GaCl], while with PhN[double bond, length as m-dash]NPh it forms [1 + 4]-cycloaddition product [(ADC)GaN(Ph)N[double bond, length as m-dash]CH] by the dearomatization of one of the phenyl rings.