title: Can bridged 1,6-X-[10]annulenes (X = SiH(2), SiMe(2), PH, and S) exist?
abstract: [structure: see text] In contrast to the 1,6-X-[10]annulenes (X = CH(2), O, NH) with delocalized forms (c), their X = PH and S counterparts favor the bisnorcaradiene structures (b). Forms b and c are close in energy with X = SiH(2) and SiMe(2). The computed nucleus independent chemical shifts (NICS), show both annulenes (c) and cyclic polyenes (a) to be aromatic. Strain-introduced structural localization, e.g., due to four bulky SiMe(3) substituents, reduces but does not eliminate aromaticity.
authors.affiliation: Department of Chemistry, Shanxi Normal University, Linfen 041004, China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Jiao
authors.forename: Nicolaas J R
authors.initials: NJ
authors.lastname: van Eikema Hommes
authors.forename: Paul
authors.initials: P
authors.lastname: von Ragué Schleyer