Double 1,2-Carbon Migration at Mixed Heavier Sn=Ge Vinylidenes

1,2-migration is one recurring isomerization reaction in organic chemistry. In contrast, double 1,2-migration remains rare and limited to transition-metal complexes. Herein, we describe the synthesis, characterization and reactivity of mixed heavier Sn=Ge vinylidenes. Double 1,2-carbon migration enables the isomerization of the stannagermenylidene (3) to the germastannenylidene (4). X-ray diffraction analysis and DFT calculations revealed that 3 and 4 feature a Sn=Ge double bond. The reaction of 3 with IMe4 (1,3,4,5-tetramethylimidazoline-2-ylidene) results in the electron redistribution in the Sn=Ge core to give the germylone-stannylene adduct (5). Moreover, treatment of 3 with 0.25 equiv. of (AlCp*)4 produces the heteronuclear aluminyl stannagermyne (6). Double 1,2-carbon migration enables the isomerization of the stannagermenylidene to the germastannenylidene. Theoretical studies reveal that the isomerization process involves stepwise carboranyl group and aryl group migration. The reactivity studies demonstrate that the stannagermenylidene undergoes intriguing electron redistribution to give the germylone-stannylene adduct upon treatment with IMe4 and readily reacts with (AlCp*)4 to give the unique heteronuclear aluminyl stannagermyne.+ image