Discrimination of Geometrical Epoxide Isomers by ENDOR Spectroscopy and DFT Calculations: The Role of Hydrogen Bonds

Abstract

EPR and ENDOR spectroscopies combined with DFT calculations have revealed the selective binding of a cis over a trans epoxide to a chiral vanadyl salen complex (see picture). Complementary DFT calculations identified a weak electrostatic interaction supplemented by multiple hydrogen-bonding contacts as the origins of this selectivity. These observations were experimentally confirmed in frozen solution by orientation selective ENDOR measurements.