Chemical Physics Letters, Vol.318, No.1-3, 142-148, 2000
Electronic spectra of the CH3C=N=CXY(X, Y=H, Cl) nitrile ylides: an ab initio multiconfigurational second-order quasidegenerate perturbation theory study
Multireference and multistate perturbation theory st second order (MC-QDPT2) based on a CASSCF wavefunction was used to study the electronic spectra of three nitrile ylides: CH3C=N=CH2, CH3C=N=CHCl and CH3C=N=CCl2. These ylides, which have an aliene-like structure, present to characteristic transitions of n -->pi* type with lambda(max) > 200 nm. The longer-wavelength absorption has low intensity, while the shorter-wavelength absorption has a relatively strong intensity. These absorptions an predicted to occur at 312 and 272 nm (CH3C=N=CH2), 356 and 283 nm (CH3C=N=CHCl), and 377 and 305 nm (CH3C=N=CCl2).