Heavy cyclopropene analogues R4SiGe2 and R4Ge3 (R = SiMetBu2) – New members of the cyclic digermenes family

1H-Siladigermirene R4SiGe2 (2a) and 1H-trigermirene R4Ge3 (2b) (R = SiMetBu2) with a GeGe double bond were synthesized by the reaction of tetrachlorodigermane RGeCl2–GeCl2R with dilithiosilane R2SiLi2 and dilithiogermane R2GeLi2, respectively. The skeletal GeGe double bond of 2a is trans-bent (51.0(2)°) with a bond distance of 2.2429(6) Å. The reaction of both 2a and 2b with CH2Cl2 resulted in the formation of unusual four-membered ring compounds 5a and 5b as a result of a ring expansion reaction. 1H-Trisilirene 7a and 3H-disilagermirene 7b with an SiSi double bond also smoothly reacted with CH2Cl2 to yield the four-membered ring systems 8a and 8b, respectively.

Graphical abstract1H-Siladigermirene R4SiGe2(2a) and 1H-trigermirene R4Ge3(2b) (R = SiMetBu2) with a GeGe double bond were synthesized by the reaction of tetrachlorodigermane RGeCl2–GeCl2R with dilithiosilane R2SiLi2 and dilithiogermane R2GeLi2, respectively. The reactions of 2a and 2b with CH2Cl2 resulted in the formation of unusual four-membered ring compounds 5a and 5b as a result of the ring expansion reaction. 1H-trisilirene and 3H-disilagermirene with an SiSi double bond also smoothly reacted with CH2Cl2 to yield the similar four-membered ring compounds.Figure optionsDownload full-size imageDownload as PowerPoint slide