Synthesis, structure and reactivity of cationic base-stabilized gallyleneiron complexes

Addition of 2,2′-bipyridine (bpy) to an acetonitrile solution of dichlorogallyliron complex FpGaCl₂ (1: Fp = (η-C₅H₅)Fe(CO)₂) afforded almost quantitatively a salt consisting of a cationic base-stabilized gallylene complex [FpGaCl·bpy]⁺ ([3a]⁺) and an anionic complex [FpGaCl₃]^- ([4]^-). Reaction of Fp′GaCl₂ (Fp′ = Fp (1), Fp* (2); Fp* = (η-C₅Me₅)Fe(CO)₂) with NaBPh₄ in the presence of a bidentate donor (Do₂) gave [Fp′GaCl·Do₂]BPh₄ where Do₂ was bpy or 1,10-phenanthroline (phen). These cationic complexes may be useful precursors for the synthesis of gallyleneiron complexes with various substituents on the gallium atom. Indeed, reaction of [Fp*GaCl·phen]BPh₄ ([5b]BPh₄) with NaS^PTol or Me₃SiS^PTol afforded the gallyleneiron complex [Fp*GaS^PTol·phen]BPh₄ ([6]BPh₄), the first example of a gallium-transition metal complex having a thiolate group on the gallium atom. The molecular structures of [5b]BPh₄ and [6]BPh₄ were determined by single crystal X-ray diffraction.