A series of phosphaalkenes, E-ArP=C(H)Ar′ (Ar = 2,6-Mes 2C6H3, Ar′ = Ph (1a); Ar = 2,6-Mes 2C6H3, Ar′ = p-C6H 4Br (2a); Ar = 4-Br-2,6-Mes2C6H2, Ar′ = Ph (3a); Ar = 4-Br-2,6-Mes2C6H2, Ar′ = p-C6H4Br (4a)) have been prepared by phospha-Wittig reactions and characterized. Exposure of these materials either to room light over an extended period of time (days) or to UV light (hours) produced equilibrium mixtures of the E and Z isomers (1b-4b) as indicated by 1H and 31P NMR spectroscopy. The structures of compounds 4a and 4b were determined by single-crystal X-ray diffraction methods. Variable-temperature 1H NMR studies of 4b indicate hindered rotation about the P-CAr bond, with ΔH‡ = 13.8 kcal/mol and ΔS‡ = 1.3 eu. The electronic structures of E- and Z-PhP= C(H)Ph have been examined using density functional theory.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry