CCL: Quantifying the Hammond postulate

 Sent to CCL by: Thomas Manz [thomasamanz-$-gmail.com]
 Dear Miquel,
 I am familiar with the series of paper you mentioned. (The year on the
 first paper should be 1991.) If I understand correctly, all of the
 examples in those papers are unimolecular reactions. It's not clear to
 me how that approach could be conveniently applied to other types of
 systems.
 Sincerely,
 Tom
 2009/11/24 Miquel Solà miquel.sola*udg.edu
 <owner-chemistry_-_ccl.net>:
 >
 > Dear Thomas,
 >
 > There is at least another universal method to quantify the transition state
 > earliness or lateness based on quantum molecular similarity measures. Some
 > references are:
 >
 > 1) J. Cioslowski, Quantifying the Hammond postulate: intramolecular proton
 > transfer in substituted hydrogen catecholate anions.
 > J. Am. Chem. Soc. 116 (1994) 6756-6760.
 > 2) M. Solà, J. Mestres, R. Carbó and M. Duran. Use of ab initio
 Quantum
 > Molecular Similarities as an interpretative tool for the study of chemical
 > reactions. J. Am. Chem. Soc. 116 (1994) 5909-5915.
 > 3) M. Solà and A. Toro-Labbé. The Hammond postulate and the
 Principle of
 > Maximum Hardness in Some Intramolecular Rearrangement Reactions. J. Phys.
 > Chem. A, 103 (1999) 8847-8852.
 >
 > Best regards,
 >
 > Miquel Solà
 >
 >
 > Thomas A. Manz thomasamanz(a)gmail.com escribió:
 >
 > Sent to CCL by: "Thomas A. Manz" [thomasamanz*gmail.com]
 > An early transition state resembles the reactants more than the products,
 > while a late transition state resembles the products more than the
 > reactants. Several postulates in chemistry and catalysis require a
 > quantitative measure of transition state lateness for their application.
 > These include the Hammond-Leffler postulate, the structure sensitivity
 > postulate, and the reactant sensitivity postulate. The Hammond-Leffler
 > postulate is taught in several college textbooks, and Hammonds 1955 article
 > describing it (J. Am. Chem.Soc. 77 (1955) 334-338.) has received more than
 > three thousand citations. However, until now there was no universal method
 > for quantifying transition state lateness from geometries along a minimum
 > energy reaction pathway.
 > A new method published in the Journal of Computational Chemistry describes
 a
 > dimensionless reaction coordinate, W, that can be used to quantify the
 > relative lateness of transition states. W varies monotonically from 0
 > (reactant) to 1 (product) along a minimum energy reaction pathway. Let WTS
 > denote the dimensionless reaction coordinate of the transition state. When
 > WTS < 0.5, the transition state is early. When WTS > 0.5, the
 transition
 > state is late. When WTS = 0.5, the transition state is equidistant between
 > reactants and products. This descriptor can be computed using only a series
 > of optimized geometries (aka images) along the minimum energy reaction
 > pathway. A minimum of three images (reactant, transition state, and
 product)
 > is required, and there is no maximum in the number of images that can be
 > used.
 > Once optimized geometries along the minimum energy reaction pathway are
 > known, the time for computing W is a small fraction of a second. (The
 > equations for computing W of each image are simple algebraic equations.)
 > A free program implementing the method is available at
 >
 > http://sourceforge.net/projects/drcs/
 > This type of analysis should be useful to those performing nudged elastic
 > band (NEB), quadratic synrchronous transit (QST), or intrinsic reaction
 > coordinate (IRC) calculations. The method is applicable to both periodic
 and
 > nonperiodic systems and can be used for reactions occuring in the
 gas-phase,
 > in liquid-phase, in solids, or on surfaces.
 > Link to the published abstract:
 > http://www3.interscience.wiley.com/journal/122682417/abstract
 > The article describes both the quantification of transition state lateness
 > and its application to several postulates in chemistry and catalysis.
 > Tom Manz
 > thomasamanz [at] gmail.comE-mail to subscribers: CHEMISTRY**ccl.net or
 use:> E-mail to administrators: CHEMISTRY-REQUEST**ccl.net or usehttp://www.ccl.net/chemistry/sub_unsub.shtml>; Search
 Messages:
 > http://www.ccl.net/chemistry/searchccl/index.shtmlhttp-:-//www.ccl.net/spammers.txt>;
 >
 > --
 >
 >  -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
 >  Miquel Solà
 >  Institut de Química Computacional i Departament de Química
 >  Universitat de Girona
 >  Campus Montilivi
 >  17071 Girona, CATALONIA (Spain)
 >  Phone +34.972.41.89.12
 >  Cellular-Phone:  +34.626.163.580
 >  FAX   +34.972.41.83.56
 >  World Wide Web: http://iqc.udg.es/~miquel/mike.html
 >  e-mail: miquel.sola**udg.es
 >  -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
 >