Subject: Summary: Intramolecular Hydrogen Bond and AIM

From: Ari Lahti IFK <[email-masked]>
Date: Sat, 14 Dec 1996 14:02:34 +0200 (EET)

Dear CCLers,

Many thanks to all who responded to my query on Intramolecular Hydrogen
Bond and AIM. According to the replies summerized below, the AIM theory 
really is applicable to the evaluation of the strength of intramolecular
hydrogen bonds. It seems worthwhile trying AIMPAC, MORPHY, or EXTREME 
if Gaussian fails to identify the critical points. I also thank prof. 
Bader and dr Bayley, working in his group, for kindly delivering a copy 
of the AIMPAC program package. 

	best wishes
	--ari lahti

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* Ari Lahti, M.D., M.Sc.                          phone: +358 2 2654951     *
* Dept. of Phys. Chem.                            fax:   +358 2 2654706     *
* Abo Akademi University                          email: [email-masked]    *
* Porthansg. 3-5                                                            *
* FIN - 20500 Abo                                                           *
* Finland                                                                   *
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My original message:

>I make calculations on a small molecule that has an imidazole ring and 
>another ring formed by an intramolecular hydrogen bond. I would like to 
>evaluate the strength of this intramolecular hydrogen bond, and I'm
>wondering if the AIM theory might be useful in this respect. 

>The charge density at the critical point of a bond is supposed to correlate
>with the strength of the bond. Is this correlation linear in the sense that
>it lets one compare the strengths of intramolecular hydrogen bonds between 
>related molecules? Would this linearity make possible the evaluation of the
>strength of an intramolecular hydrogen bond in absolute terms also,
>through comparison of the charge density at the critical point of the
>system under investigation to that of a known model system? 

>I have made some preliminary calculations using the AIM card of
>Gaussian94. My calculations always end up with 'Hopf-Poincare condition not 
>satisfied', possibly because the program cannot handle the ring structures 
>of my molecule. The ring points are thus not given. However, the critical
>points of the covalent bonds and the intramolecular hydrogen bond are
>indicated. Are these results useful, or does the Hopf-Poincare error
>message mean that even data concerning these bond critical points are 
>corrupted? 

The replies:

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>From [email-masked] Tue Dec 10 04:19 EET 1996

Dear Ari

There is a paper by Koch & Popelier, in JPC last year which you will find
useful, as it deals with AIM and H-bonding. (sorry I don't have the full
reference in front of me, only a preprint) It also has references to other
AIM studies of H-bonding. A strong correlation between rho at the X--H 
(hydrogen bond) bond critical point and the bond strength is evident from
these studies. For an AIM study of intramolecular H-bonding see:
  D.K. Taylor, I. Bytheway, D.H.R. Barton, C.A. Bayse, M.B. Hall 
"Toward the Generation of NO in Biological Systems: Theoretical Studies of 
the N2O2 Grouping" Journal of Organic Chemistry, 1995, 60, 435-444.

As for your output, I'd suggest running either MORPHY or EXTREME on the
molecule to see if they find the ring critical point - you might need to
search "by hand" although MORPHY is usually good at picking up these rogue
critical points. If that fails you might need to look at the basis set and
check that your total charge density is ok.

Hope this is of some use.

Ian Bytheway
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>From [email-masked] Tue Dec 10 02:01 EET 1996

	Ari:

	You can find examples of the use of properties of the total charge
density to characterize intermolecular interactions in Bader's book

	R. F. W. Bader, Atoms in Molecules - A Quantum Theory, Oxford
	University Press, Oxford, 1990.

	[http://www.chemistry.mcmaster.ca/faculty/bader]

and the work of Bader and M. T. Carroll.  For the studies of the
relationship between the properties of critical points and bonding
strength, you might want to look at the work of R. J. Boyd.

	The topology of the charge density in the systems you discussed
should be relatively straightforward.  I don't know why you had difficulty
with Gaussian, but you might want to look into getting the latest versions
of Bader's AIMPAC program suite.  Write Bader at

	[email-masked]

You might also want to investigate P. L. A. Popelier's program MORPHY
which provides a very nice and automated procedure for searching the
topology.

	MORPHY, a program for an automatic Atoms in Molecules Analysis, PLA
	Popelier, Comp.Phys.Comm, 1996 93, 212. 
	
	[http://uchsg11.ch.umist.ac.uk/popelier.htm]

	Good Luck...

	Keith

+-| Keith E. Laidig, Ph.D.,  Research Associate
+-| Department of Medicinal Chemistry 
+-| University of Washington,  Seattle,  WA  98195-7610
+-| E-Mail: [email-masked]             Phone#: (206) 616-2780
+-| WWW: http://weber.u.washington.edu/~laidig  FAX  #: (206) 685-3252
_____________________________________________________________________________

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>From [email-masked] Tue Dec 10 15:11 EET 1996

Dear Ari,

We did some semiempirical and ab initio calcs on similar systems a
year or so ago (see "Modeling the Hydrogen Bond", ACS Symposium Series 569,
Doug Smith, editor, 1994, pages 269-276).  Actually, the whole volume
is a good summary of H-bond modeling.
For our imidazole/oxazole type systems, we found that AM1 gave really
poor results.  In some cases, it even missed some H-bonds altogether
as I recall.  When we did ab initio calcs, even including correlation,
we found these H-bonds to be very strong indeed (among the strongest
H-bonds), and this correlated well with experiment.
Good luck.
Doug Dudis
Polymer Branch
Wright Laboratory - Materials Directorate
Dayton, Ohio USA
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>From [email-masked] Thu Dec 12 14:20 EET 1996

Dear Ari Lahti

  In our Department O. Mo and M. Yanez have made calculation
of hydrogen bonds and related the streghth of the bond with properties of
the bond critical points.

  Have a look at:

   O.Mo,  M. Yanez and J. Elguero
           J. Chem. Phys. 97, 6628 (1992)
           Theochem 314, 73 (1994)

  We have found sometimes problems with gaussian94 when locating the 
critical points because the Hopf-poincare condition was not satisfied, I 
suggest you to use Bader´s programs instead.

  Hope this help

  Manuel Alcami
  Departamento de Quimica
  Facultad de Ciencias C-9
  Universidad Autonoma de Madrid  
  28049-Madrid (Spain)
  Phone: 397-38-57  Fax: 397-41-87

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>From [email-masked] Wed Dec 11 18:27 EET 1996

dear dr. lahti,
   i just returned from europe and found your ,message.  yes, we will send
you a copy of aimpac and you have no trouble finding cps .  the gaussian 94
version of aimpac has problems.  use outr program.  we have used the theory
to study h-bonds in a large number of systems.  some refeeeeernces are Mol.
Phys. 1988, vol 65, 695: Chem. Phys. Letts.  189, 542, 1992.  mol phy. 1988,
63, 387.  you will find in these papaers and in other references given
there, results which show a linear corel;ation of h-bpond strength with
density at cp and with other properteis obtained from the thoery.  best
regards, richard bader.

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