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, GatBu3). 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 [GaIII{PPh(2-SC6H4)-κ2S,P-μ-(2-SC6H4)-κS′}2]2(μ3-H)2GaII2 (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.