Electronic properties, polymerization, and cycloaddition of 3,4,7,8-tetragermacycloocta-1,5-diyne and related compounds

Alkynes Between Main Group Elements: From Dumbbells via Rods to Squares and Tubes

“…The photoelectron spectra of bis(trimethylsilyl)di- and triacetylene show a shift of the π-bands toward lower energy when compared to the t -butyl substituted congeners . The results when acetylene and 1,3-butadiyne were substituted with (H 3 C) 3 Ge , and (H 3 C) 3 Sn were similar.…”

“…Larger cycles 187 and 188 could be obtained by the reaction of 185 with tetracyanoethylene (TCNE) in dichloromethane; most of them were electronically and structurally characterized . In the more polar solvent, acetonitrile, using only catalytic amounts of TCNE, a polymerization takes place . This oligomerization/polymerization process can be rationalized in the following way: A Ge−Ge σ bond is more susceptible to electrophiles than a Si−Si σ bond.…”

“…174 In the more polar solvent, acetonitrile, using only catalytic amounts of TCNE, a polymerization takes place. 175 This oligomerization/polymerization process can be rationalized in the following way: A Ge-Ge σ bond is more susceptible to electrophiles than a Si-Si σ bond. Thus TCNE is inserted in the Ge-Ge bond, mediating the oligomerization process.…”

Singly Bonded Catenated Germanes: Eighty Years of Progress

“…228 At elevated temperatures, an additional tricyclic species is formed in the product mixture in 3% yield (Scheme 65). 229 Some large heterocyclic systems have been prepared, including the tetragermacyclooctadiyne 155, which was generated from the acetylene-functionalized digermane 154 (Scheme 66) 230,231 The reaction of 155 with tetracycanoethylene (TCNE) results in a charge transfer complex that exhibits an absorption maximum in the visible region at 488 nm. If the mixture of 155 and TCNE is allowed to stand for 2 days, oligomerization of 155 occurs to furnish the twelvemembered and sixteen-membered heterocycles 156 and 157 (respectively).…”