? re H-bonds

["Hr Dr. S. Shapiro" <toukie - at - zui.unizh.ch>]

 Dear Colleagues;
      I have a series of compounds for which I wish to be able to estimate
 strengths of intramolecular hydrogen bonds.  These compounds all have the
 following basic structure:
              H    R
            /     /
          X     :O
          |     /
          C----C
          |
        ------
 and I would like to be able to calculate the approximate intramolecular hy-
 drogen bond energy between the H atom and the :O atom.  I know the distance
 between H and O and between H and the lone electron pair (:); I also know the
 values of the torsion angles corresponding to H-X-C-C, :-O-C-C, O-C-C-X,
 R-O-C-C, X-H-:-O, and H-:-O-C.  Given this information, is there a formula
 for estimating the strength of the intramolecular hydrogen bond H---: or
 H---O?  Of course, any relevant references would also be most welcome.
      Thanks in advance to all responders.
 Sincerely,
 S. Shapiro
 ZH
 toukie - at - zui.unizh.ch