Molecular orientation around the fluoride ion dissolved in methanol and formamide
Abstract
The 19F nuclear magnetic relaxation times of solutions of RbF in CH3OH and in the isotope-labelled methanols CH3OD and CD3OH have been measured as a function of the salt concentration. Evaluation by standard methods involving the expression for the intermolecular rates yields the F––CH3 and F––OH distances. The same procedure for F– in the formamides HCONH2, DCONH2, HCOND2 and CDOND2 yields the F––H and F––H2N distances. Knowledge of the geometry of the molecule then allows the determination of the orientation relative to F–. In methanol we find an H-bonding orientation and in formamide a compromise between H-bonding and dipole alignment.