Monosolvation of R-1-phenyl-2,2,2-trifluoroethanol with amines: configurational effects on the excitation, ionization, and fragmentation of diastereomeric complexes.

Wavelength and mass selected resonant two-photon ionization spectra of mol. clusters between R-1-phenyl-2,2,2-trifluoroethanol (FER) and methylamine (M) or the enantiomers of 2-aminobutane (AR and AS) were recorded after supersonic mol. beam expansion and analyzed with the aid of ab initio MO calcns. The exptl. results agree with theor. calcns. pointing to the predominance of the two most stable conformers of monosolvated FER whose CF3 group establishes intense NHF interactions with the selected amines so as to orient them away from the arom. ring. This reduces the enantioselectivity of FER toward the 2-aminobutane enantiomers as compared to that exhibited by the R-1-phenylethanol (ER) analog, where obviously NHF interactions are absent.