Annulated Carbocyclic Gallylene and Bis-Gallylene with Two-Coordinated Ga(I) Atoms

The first carbocyclic gallylene [(ADC)2Ga(GaI2)] and bis-gallylene [(ADC)Ga]2 (ADC = PhC{N(Dipp)C}2; Dipp = 2,6-iPr2C6H3) featuring a central C4Ga2 ring annulated between two 1,3-imidazole rings are prepared by KC8 reductions of [(ADC)GaI2]2. Treatment of [(ADC)Ga]2 with Fe2(CO)9 affords complex [(ADC)GaFe(CO)4]2 in which each Ga(I) atom serves as a two-electron donor. [(ADC)Ga]2 activates white phosphorus (P4) and the Csp2–F bond of aryl fluorides (ArF) to yield compounds [(ADC)Ga(P4)]2 and cis-/trans-[ADC)GaF(Ar)]2, respectively. [(ADC)Ga]2 undergoes oxidation with (Me2S)AuCl to give [(ADC)GaCl2]2, while with PhN=NPh it forms [1+4]-cycloaddition product [(ADC)GaN(Ph)N=C6H5]2 by the dearomatization of one of the phenyl rings.