C,C-diacetylenic phosphaalkenes as heavy diethynylethene analogues.
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5c-f. The title compounds represent rare examples of diethynylethenes in which a constituting methylene has been replaced by a phosphorus center.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.
Oberg
Elisabet
E
Department of Photochemistry and Molecular Science, Angstrom Laboratories, Uppsala University, Box 523, 75120 Uppsala, Sweden.
Schäfer
Bernhard
B
Geng
Xue-Li
XL
Pettersson
Jenny
J
Hu
Qi
Q
Kritikos
Mikael
M
Rasmussen
Torben
T
Ott
Sascha
S