Stabilisation of an inorganic digallane by the phosphinobisthiolato P,S,S pincer ligand PPh(2-SC6H4)2

Abstract

The pincer ligand PPh(2-HSC₆H₄)₂ reacts with GaCl₃ in the presence of triethylamine to yield the anionic gallium complex [NEt₃H][Ga{PPh(2-SC₆H₄)₂-κ³S,S′,P}{PPh(2-SC₆H₄)₂-κ²S,S′}] (1), which undergoes cation exchange with PPh₄Cl to give [PPh₄][Ga{PPh(2-SC₆H₄)₂-κ³S,S′,P}{PPh(2-SC₆H₄)₂-κ²S,S′}] (2). Neutral complexes GaR{PPh(2-SC₆H₄)₂-κ³S,S′,P} [R = Me (3), ^tBu (4)] were obtained by reaction of PPh(2-HSC₆H₄)₂ with trialkyl gallium compounds (GaMe₃, Ga^tBu₃). Compound 4 is light-sensitive and decomposes in daylight or under UV irradiation. Three decomposition products could be isolated: tetranuclear hydrido-bridged mixed-valent gallium(II)–gallium(III) complex [Ga^III{PPh(2-SC₆H₄)-κ²S,P-μ-(2-SC₆H₄)-κS′}₂]₂(μ₃-H)₂Ga^II₂ (Ga–Ga) (5), gallium(II) complex [Ga{PPh(2-SC₆H₄)₂-κ³S,S′,P}]₂ (Ga–Ga) (6), and sulfido-bridged dinuclear complex [Ga{PPh(2-SC₆H₄)₂-κ³S,S′,P}]₂(μ-S) (7). The molecular structures of 2–7 are described.