Application of Different Spectral Methods to Examine Structure of the Complexes Found in the Cycloaddition Reactions of 4-Trifluoromethylbenzonitrile Oxide to Olefins

Structure of chiral complexes of ytterbium triflate with (R)-1,1′-bi-2-naphthol and 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose, highly effective catalysts in enantioselective cycloaddition reaction of 4-trifluoromethylbenzonitrile oxide to Z-2-pentenol and 2-methoxyphenylcrotonamide, was examined with the application of electron paramagnetic resonance (EPR), 1H, 13C, 19F nuclear magnetic resonance, infrared spectroscopy, mass spectroscopy, and spectrofluorimetry. EPR spectroscopy has demonstrated the presence of the octahedral and tetrahedral environments of the complexes. Observation of strong emission bands proved electron delocalization to the remote areas which enabled an interaction of the ligand with the rest of the catalytic complex.