Silicon Version Of A Vinyl Cation Debuts

Chemists in Japan have unveiled the latest addition to the collection of heavy group 14 element analogs of carbon compounds: a disilicon version of the vinyl carbocat­ion (J. Am. Chem. Soc., DOI: 10.1021/ja210669n). The University of Tsukuba team led by Akira Sekiguchi prepared the disilenyl cation shown by methylating a known disilyne complex, RLSi=SiR:, where R is a bulky silyl substituent and L is an N-heterocyclic carbene ligand incorporated for added stability. By studying the structure and bonding of the crystalline yellow disilenyl triflate salt, the researchers found that the carbene enables the cationic charge to be delocalized throughout the carbene-silicon skeleton. Heavy group 14 cations have become an important topic in main-group chemistry during the past decade as chemists have become proficient at preparing isolable double- and triple-bonded silicon, germanium, tin, and lead analogs of alkenes and alkynes. “Disilenyl cations are intriguing targets,” Sekiguchi says, “because they possess both a silyl cation and a disilene—two highly reactive functional groups. As such, they should have interesting physical, electronic, and reactive properties and lead to further discoveries in silicon chemistry.”