Assignment of absolute configurations of chiral phospholene oxides by UV/CD spectroscopy using TD-DFT quantum chemical calculations and singular value decomposition approach for the analysis of the spectra

The UV absorption and circular dichroism (CD) spectra of P-chiral 1-substituted-3-methyl-3-phospholene 1-oxides were analyzed on the basis of quantum chemical calculations aiming at the assignment of the absolute configurations of the molecules. Geometry optimization and determination of the most stable conformers were performed using density functional theory (DFT). The energies, oscillatory strengths and rotatory strengths of the singlet electronic transitions have been determined by time-dependent DFT (TD-DFT) method. For the qualitative description of the excitation patterns, the various natural molecular orbitals characteristic for the excitation process have been determined by using a singular value decomposition (SVD) algorithm recently proposed by Mayer [I. Mayer, Chem. Phys. Lett. 437 (2007) 284].