title: C,C-diacetylenic phosphaalkenes as heavy diethynylethene analogues.
abstract: A series of C,C-diacetylenic phosphaalkenes 1b-e has been prepared from 1-chloropenta-1,2-dien-4-ynes 6b-e in a reaction with Mes*PCl(2) (Mes* = 2,4,6-((t)Bu)(3)Ph) in the presence of LDA. Under identical conditions, isomeric butadiyne-substituted phosphaalkenes 2c-f can be obtained from 3-chloropenta-1,4-diynes 5c-f. The title compounds represent rare examples of diethynylethenes in which a constituting methylene has been replaced by a phosphorus center. The formation of both isomers can be rationalized by a common pathway that involves isomeric allenyllithium species. Spectroscopic, electrochemical, and theoretical investigations show that the phosphorus heteroatoms are an intrinsic part of the compounds' pi-systems and lead to decreased HOMO-LUMO gaps compared to those in all-carbon-based reference compounds.
authors.affiliation: Department of Photochemistry and Molecular Science, Angstrom Laboratories, Uppsala University, Box 523, 75120 Uppsala, Sweden.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Oberg
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schäfer
authors.forename: Xue-Li
authors.initials: XL
authors.lastname: Geng
authors.forename: Jenny
authors.initials: J
authors.lastname: Pettersson
authors.forename: Qi
authors.initials: Q
authors.lastname: Hu
authors.forename: Mikael
authors.initials: M
authors.lastname: Kritikos
authors.forename: Torben
authors.initials: T
authors.lastname: Rasmussen
authors.forename: Sascha
authors.initials: S
authors.lastname: Ott