Subject: Agostic interaction

From: Yubo Fan <[email-masked]>
Date: Thu, 10 Aug 2000 13:01:04 +0800

Hi, All CCLers,

I have met a keyword, agostic interaction, recently. It cannot be found
in various dictionaries. To my knowledge, it means weak intermolecular
interaction. I really don't understand it clearly. The problem is what
types of intermolecular interactions can be regarded as agostic
interaction. Could anybody give me the definition and examples?

Thanks in advance

Y. Fan

--
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Yubo Fan                         Email: [email-masked]
Organic Synthesis Lab
The Department of Chemistry
Fudan University                 Phone: 8621-65648139
No. 220 Handan Road              Fax:   8621-65641740
Shanghai, 200433
P. R. China
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From: Geoff Hutchison <[email-masked]>
Date: Thu, 10 Aug 2000 11:37:27 -0500 (CDT)

The term "agostic interactions" is typically used in the context of
inorganic and organometallic ligand systems. The term refers to
an interaction between a metal center and usually a C-H bond and is
typically indicated in diagrams with a dotted line or arrow from the H
atom to the metal center. The M-H distance is usually close and the
C-H (or other) bond is stretched somewhat.

I imagine you can find the term in almost any textbook on inorganic
chemistry along with some classic examples. However, a quick search for
"agostic interaction" also turned up the following URL:
<http://www.ilpi.com/organomet/agostic.html>

Cheers,
-Geoff Hutchison
Northwestern Chemistry

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From: Gregori Ujaque <[email-masked]>
Date: Thu, 10 Aug 2000 13:06:15 -0700 (PDT)

Hi,

The 'agostic' term was initially used for intramolecular covalent
interactions between the metal center and the C-H group
(in orgamometallic complexes). Nowadays, this term is used to design
any interaction between the a sigma bond which belongs to a ligand
already bonded to the metal center, and the metal center.

You can take a look on the original papers, where the agostic
term was first introduced:

- Brookhart M, Green MLH J. Organomet. Chem. 1983, 250, 395.
- Brookhart M, Green MLH, Wong L, Prog. Inorg. Chem. 1988, 36, 1.

Some other interesting readings:

- Ujaque G, Cooper AC, Maseras F, Eisenstein O, Caulton GC
J. Am. Chem. Soc. 1998, 120, 361.
- Koga N, Morokuma K, J. Am. Chem. Soc. J. Am. Chem. Soc. 1988, 110, 108.
- Crantree RH, Hamilton DG, Adv. Organomet. Chem. 1988, 28, 299.

I hope it helps,

Gregori
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Gregori Ujaque

Department of Chemistry & Biochemistry   [email-masked]
University of California, Los Angeles 	 Phone:	1.310.825.0269
405 Hilgard Ave. LA, CA 90095-1569	 Fax:	1.310.206.1843

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On Thu, 10 Aug 2000, Yubo Fan wrote:

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