From: D. Boyd <dboyd@iupui.edu>

Date: Fri, Dec 17, 2010 at 8:23 PM

Subject: Hydrogen Bond Reformulation

To: "Elangannan Arunan (IUPAC)" <arunan@ipc.iisc.ernet.in>, "Steve Scheiner

Cc: "D. Boyd" <dboyd@iupui.edu>

Gentleman:

Last month, I saw the article in Chemical & Engineering News magazine about

Hydrogen Bond Reformulation. I would like to share my thoughts on this

subject.

The IUPAC task group proposes this definition: "The hydrogen bond is an

attractive interaction between a hydrogen atom from a molecule or a

molecular fragment X–H in which X is more electronegative than H, and an

atom or a group of atoms in the same or a different molecule, in which there

is evidence of bond formation."

I see no problem with making the definition more expansive. However, I do

have a problem with the way the new definition is worded.

If you boil down the above definition grammatically it says "The hydrogen

bond is an attractive interaction ... in which there is evidence of bond

formation." In effect, you are saying that a bond is a bond. As you know,

there are different kinds of bonds, covalent, etc.

I recommend that the terminology at the end of the new definition be revised

to avoid a circuitous argument. My suggestion would be to replace "bond

formation" with "stabilizing association".

Thus, I am proposing something like:

"The hydrogen bond is an attractive interaction between a hydrogen atom from

a molecule or a molecular fragment X–H in which X is more electronegative

than H, and an atom or a group of atoms in the same or a different molecule,

in which there is evidence of stabilizing association."

Thank you.

Cordially, Don

Donald B. Boyd, Ph.D.

Research Professor of Chemistry

Editor Emeritus, Reviews in Computational Chemistry

Executive Committee, Gordon Research Conference on Computational Chemistry

Department of Chemistry and Chemical Biology

Indiana University-Purdue University at Indianapolis

402 North Blackford Street

Indianapolis, Indiana 46202-3274, U.S.A.

Tel. 317-274-6891, Fax 317-274-4701