Chalcogenido-Dimethylgallates and -Indates DMPyr2 [Me2 M(μ2 -E)]2 (M=Ga, In; E=S, Se): Building Blocks for Higher and Lower Order Chalcogenidoindates.

Metalation of the anions in the ionic liquids DMPyr[SH] and DMPyr[SeH] (DMPyr=1,1-dimethylpyrrolidinium) by trimethylgallium and trimethylindium is investigated. The reaction proceeds via pre-coordination of [EH]- , methane elimination and formation of an unprecedented series of chalcogenido metalates DMPyr2 [Me2 M(μ2 -E)]2 (M=Ga, In; E=S, Se). These show the presences of dinuclear dianions with four-membered ring structures displaying highly nucleophilic bridging chalcogenide ligands in their crystallographically determined molecular structures. Some representative reactions of these building blocks with amphoteric electrophiles were studied: Addition of two equivalents of E(SiMe3 )2 (E=S, Se) to the indates DMPyr2 [Me2 In(μ2 -S)]2 and DMPyr2 [Me2 In(μ2 -Se)]2 leads to a cleavage of the ring, E silylation and formation of mononuclear, monoanionic indates DMPyr[Me2 In(SSiMe3 )2 ], DMPyr[Me2 In(SeSiMe3 )2 ], and even a mixed sulfido-selenido dimethylindate DMPyr[Me2 In(SSiMe3 )(SeSiMe3 )]. Reaction of DMPyr2 [Me2 In(μ2 -S)]2 with two equivalents of Lewis acid Me3 In leads to charge delocalization, ring expansion and formation of six-membered ring DMPyr3 [Me2 In(μ2 -S-InMe3 )]3 . The latter is a key intermediate in the formation of dianionic sulfidoindate DMPyr2 [(Me2 In)6 (μ3 -S)4 ] displaying an unusual inverse heteroadamantane cage structure with four capping sulfido ligands.