From owner-chemistry@ccl.net Thu Oct 17 08:28:00 2024 From: "Jean-Pierre DJUKIC djukic|,|unistra.fr" To: CCL Subject: CCL: [EXTERNAL] CCL: ionization / equilibrium / solvation Message-Id: <-55232-241017082557-25827-uHhJDixoloLEztZzXrGgqA() server.ccl.net> X-Original-From: Jean-Pierre DJUKIC Content-Language: fr Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8; format=flowed Date: Thu, 17 Oct 2024 14:25:44 +0200 MIME-Version: 1.0 Sent to CCL by: Jean-Pierre DJUKIC [djukic|unistra.fr] "But, is there also a way to obtain *absolute* values comparable with the experiment?" The answer to this question  is: (another question)  what do you call "absolute" ? 1) one must be certain that "experiment" provides a correct assessment of the enthalpy of the said reaction.  With ionic species, the ionic force and its effect upon thermodynamics are rarely addressed, while it is clearly the key to provide theoreticians with reliable "reference" values of thermodynamic data. 2) ionic systems pose a major challenge in this sense (both at the theoretical and exptl level), always and I doubt that you may get perfectly reliable data for the kind of reaction you deal with, without investing efforts into the cross validation of the thermochemistry by different independent exptl methods (before even putting theory at test), 3) situations where Exptl and Theorl data do match often occur with neutral molecular systems where ionic species do not weight significantly in the thermochemistry and when the reaction is studied  in weakly interacting solvents (when the solvent is not "participating" somehow to the reaction).  We have observed this in several cases with transition metal complexes and with organic reactions catalyzed by transition metal complexes. How you match the result of theory with an exptl "reference" requires primarily to solve the question of the reliability of the said "reference". -- +++++++++ Directeur de Recherche au CNRS Directeur du Laboratoire de Chimie et Systémique Organométalliques -x-UMR 7177 - Institut de Chimie de Strasbourg 4 rue Blaise Pascal 67000 Strasbourg Cedex https://orcid.org/0000-0003-3196-4921 ++++++++++++++++++++