L'hydrolyse acide (HF) des mtsitylmkthoxygermanes Mes,Ge(OMe),, conduit aux mtsitylfluorogermanes Mes,GeF,., prtcurseurs synthttiques de germanes encombrks et d'esptces du germanium i basse coordinence. La lithiogermolyse de leur liaison germanium-htttrotlkment conduit tgalement aux digermanes correspondants. Les mksitylmkthylthiogermanes Mes,Ge(SMe),., ont Ctt kgalement synthktis&s sous catalyse radicalaire par action des hydrogermanes Mes,GeH,, sur le dimithyldisulfure rtactif spkcifique de radicaux centrogermaniks ou de germyltnes.Un certain caracttre d'instabilitt apparait dans la skrie monomCsitylCe, sttriquement la moins protkgke dans laquelle nous avons observk des rtactions de redistribution-symttrisation, d'klimination cyclisante et de transfert monotlectronique en prksence de nucltophiles (RMgX).Acid hydrolysis (HF) of mesitylmethoxygermanes Mes,Ge(OMe),, leads to mtsitylfluorogermanes Mes,GeF,, often a necessary step for the synthesis of sterically hindered germanium centers, precursors of germanium species in low coordination state. The lithiogermolysis of the germanium heteroelement bond in these compounds leads to digermanes formation. The mesitylmethylthiogermanes Mes,Ge(SMe),, were obtained in radical initiated synthesis from reactions between Mes,GeH,, and dimethyldisulfide, a specific trapping reagent for germanium centered radicals and germylenes have been also synthesized.The monomesityl germanium series less sterically hindered shows some instability: redistributionsymetrisation reactions, cyclo-elimination and SET reactions in the presence of nucleophiles (RMgX) have been observed.