Computer simulation inverse Raman and far infra-red study of rototranslational correlation in optically active molecules: Part 2; 1,1 fluoroiodoethane, 3 methyl cyclopentanone and 3 methylcyclohexanone

Abstract

Abstract Computer simulation is used to investigate the statistical correlation between the molecular centre of mass velocity ( v ) and molecular angular momentum ( J ) of the optically active molecule 1,1 fluoroiodoethane in the liquid state. Of the nine elements of the moving frame correlation matrix v (t) J T(o)>m, the diagonal elements vanish by symmetry for all t. The other elements exist, in principle, for t > o, but the (1,3) and (3,1) elements are small in magnitude, and therefore buried in the computer noise, for both the R and S enantiomers and their racemic mixture. The molecular dynamical nature of the two enantiomers is therefore almost identical in the laboratory and any moving frame of reference. This implies that the laboratory frame autocorrelations of each enantiomer are similar to those in the racemic mixture, in marked contrast to 1,1 fluorochloroethane [12] where differences in the structure of the (1,3) and (3,1) elements for each enantiomer lead to large and observable differences between laboratory frame autocorrelations in either enantiomer and their racemic mixture. These differences are direct measures of rotation/translation correlation on a fundamental single molecule level. The simulation is supported by measurements in the far infra-red on the (+) enantiomers and racemic mixtures of 3 methyl cyclohexanone and 3 methyl cyclopentanone in the liquid state at 293K.