title: Oligomerization of N-Heterocyclic Silylene into Zwitterionic Silenes.
abstract: N-Heterocyclic carbenes (NHC's) are known to serve as efficient substrates for the stabilization of various transient species possessing low-valent Group 14 elements and for the generation of double E=C bonds. Herein, we report that the thermal tri- and tetramerizations of pyridoannulated silylene 1 lead to the formation of remarkably stable silenes 2 and 3 featuring zwitterionic distribution of electron density. Co-oligomerization of 1 and its germanium analogue gives a related tetrameric product 4 containing low-valent germanium atom stabilized by binding with the partial carbene-character C atom. Bonding situations in 2-4 are best described as silene or germene with the significant zwitterionic distribution of electron density. The singlet diradical electronic state of 2 is 10 kcal mol-1higher than the ground state configuration.
authors.affiliation: P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA, 19104, USA. avzabula@gmail.com.|Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, WI, 53706, USA. avzabula@gmail.com.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Zabula
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, WI, 53706, USA.
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Guzei
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, WI, 53706, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: West
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St., Chicago, IL, 60616, USA.
authors.forename: Jingbai
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Chemistry, Illinois Institute of Technology, 3101 S. Dearborn St., Chicago, IL, 60616, USA. arogache@iit.edu.
authors.forename: Andrey Yu
authors.initials: AY
authors.lastname: Rogachev
keywords: X-ray diffraction; carbene analogues; germanium; reactivity; silicon