Gallium and indium compounds of sulphur donor ligands: Pyridine-2-thiolates and diphenylthiophosphinates

Article abstract of DOI:10.1016/0277-5387(95)00253-O

The reaction of GaR₃ (R = ^tBu, Me) with 1, 2, or 3 molar equivalents of 2-mercaptopyridine (HSpy) yielded Ga(R)₂(Spy) [R = ^tBu (1), Me(2)], Ga(R)(Spy)₂ [R = ^tBu (3), Me (4)], and Ga(Spy)₃ (5), respectively. Reaction of GaCl₃ and HSpy in the presence of NEt₃ does yield Ga(Spy)₃ if excess HSpy is employed, otherwise Ga(Cl)(Spy)₂ (NEt₃) (6) may be isolated. The indium compound, In(Spy)₃ (7), may be prepared both in an analogous manner to that for compound 5, but also from the reaction of HSpy with either InCl or InCl₃ in the presence of NEt₃. In all the compounds, except compound 3, the 2-mercaptopyridine acts exclusively as a chelating ligand. Reaction of Ga(^tBu)₃ with Ph₂P(S)(SH) yields [Ph₂P(S)S]₂ but only traces of the expected product [(^tBu)₂Ga(μ-S₂PPh₂)] ₂(8). In contrast, reaction of Ga(^tBu)₃ with HO(S)PPh₂ (E = S, O) yields the dimeric compounds [(^tBu)₂Ga(μ-O(E)PPh₂)]₂, E = S (9), O (10). Compound 9 exists as a mixture of head-to-head (9a, syn) and head-to-tail (9b, anti) isomers due to the asymmetry of the bridging ligand. Reaction of GaCl₃ with three molar equivalents of Na(S₂PR₂) ? 2(H₂O), R = Me, Et, yields the tris-dithiophosphinate compounds, Ga(S₂PR₂) ₃, R = Me (11), Et (12). All new compounds have been characterized by NMR and IR spectroscopy and mass spectrometry. In addition, the molecular structures of compounds 4 and 10 have been determined by X-ray crystallography.