From mes@atlas.chemistry.uakron.edu  Fri May 28 20:49:04 1993
Date: Sat, 29 May 93 00:49:04 EDT
From: mes@atlas.chemistry.uakron.edu (Mary Ellen Scott)
Message-Id: <9305290449.AA24433@atlas.chemistry.uakron.edu>
To: chemistry@ccl.net
Subject: repsonse ot OH---FC


Dear netters,
        
Here are the responses to my query for information on 
O-H...F-C) bonding. 
        
From: (Dr.) Dave Winkler <dave@carbon.chem.csiro.au>
Subject: Calcs on hydrogen bonds
        
I did some simple conformational calculations on 2-substituted ethanols to 
assess whether AM1 or PM3 did a better job of modelling hydrogen 
bonding.  From memory I found PM3 better.  I can probably go back 
to my notebook if you want more.  
----
        
From: Gertjan Boks <boks@far.ruu.nl>
Subject: Re: Hydrogen bonding
        
To my present knowledge hydrogen bonds donated by an oxygen to a fluorine
bonded to carbon have never been observed experimentally nor theoretically.
The assumption that they do exist is for instance been made in studying 
carbohydrate - protein complexes where a sugar hydroxyl group has been
replaced by a fluorine (Vermersch et al, J.Mol.Biol.,226,923-929 (1992).
        
Searches in the Cambridge Structural Database for OH..F-C hydrogen bonds
nor ab-initio calculations supported the existence of these hydrogen
bonds. This information came to me from Jan Kanters from the Bijvoet
Center for Biomolecular Research in Utrecht, the Netherlands. He is an
expert in the field of hydrogen bonds. The studies he mentioned have
not been published however.
-----
        
From: Janne Nieminen <Janne.Nieminen@csc.fi>
Subject: RE: hydrogen bonding
        
I have just submitted M. S. about conformers of fluoroacetic acid and 
chloroacetic acid to J. Phys. Chem. (I used matrix isolation technique 
and ab initio calculations.) At PM2/6-311G** level the energy difference 
between conformers having C=O---O-H interaction and conformer having 
C-F---O-H interaction is ca. 5 kJ/mol. The conformer having neither
intermolecular interaction is ca. 30 kJ/mol higher in energy. 
(These conformers have Cs symmetry). If you are more interested in these 
results I could FAX or mail more. 
-----
        
From: jabs@chemie.uni-halle.dbp.de
Subject:  (O-H..F-C)
        
for calculation of intra- and intermolecular hydrogen bond
O-H..F-C:  L.A.Curtiss, Int.J.of Quantum Chemistry,
           Quantum Chemistry Symposium 11(1977)459
                (CF3CH2OH monomers and dimers)
 
for IR spectroscopy
                   M.Plass and A.Kolbe, J.Mol.Struct. 267(1992)21
                             (1.1.1.3.3.3-hexafluoropropanol)
 
        Andreas
 
From: raman@bioc01.uthscsa.edu (C.S.RAMAN)
Subject: Re: Hydrogen bonding
 
Emsley et al. ( J. Am. Chem. Soc., 103, 14 [1981]) found evidence for
strong hydrogen bonding of F- by amides (R-CO-NH2) by 'ab initio
calculations and from NMR and IR studies of reactions products of
strong solutions of amides and F-.
        
This is one of the most interesting and conclusive studies that I know
of; but if you are interested in hydrogen bonding of F- in the case of
biological systems, see the work by Joe Kraut et al. ( J. Biol. Chem.
259, 12984 [1984]).
-----
From: biocad!paganini.biocad.com!scott@sgi.com (Scott Kahn)
Subject: O-H...F-C
        
All of the references that I have use HF or F- as the acceptor. I would be
interested if you obtain numbers for fluorocarbon H-bonding.
-----        
 
Thanks Again,
  and more responses are always welcome
      Mary Ellen