From owner-chemistry@ccl.net Thu May 13 09:20:00 2010 From: "Ahmed El-Nahas amelnahas!=!hotmail.com" To: CCL Subject: CCL: Binding Enthalpy in vacuum and solvent Message-Id: <-41848-100513004054-1588-F8MrUIawu1/bKScXRlizng]![server.ccl.net> X-Original-From: Ahmed El-Nahas Content-Type: multipart/alternative; boundary="_b1a83c85-6f6b-43cd-97d7-4aad447bd94e_" Date: Thu, 13 May 2010 04:08:04 +0000 MIME-Version: 1.0 Sent to CCL by: Ahmed El-Nahas [amelnahas~!~hotmail.com] --_b1a83c85-6f6b-43cd-97d7-4aad447bd94e_ Content-Type: text/plain; charset="windows-1256" Content-Transfer-Encoding: 8bit People add solvent (in term of PCM) to the reactants and products; the solvation of bar metal ions releases a lot of kcal/mols at the expense of the total reaction enthalpy. If you look at the energy of solvation of the ligand, metal ion and complex, separately, you will realize this fact. I have a similar situation with a difference of about 150-300 kcal/mol between gas phase and solution, depending of your metal ion, ligand and the resulting complex. ============================= Professor Ahmed El-Nahas Physical Chemistry (Quantum Chemistry) Computational Chemistry Unit (CCU) Chemistry Department Faculty of Science El-Menoufia University Shebin El-Kom Egypt Email: amelnahas*_*hotmail.com Tel: +2-016-4607974; +81-09062124377 ============================== > From: owner-chemistry*_*ccl.net > To: amelnahas*_*hotmail.com > Subject: CCL: Binding Enthalpy in vacuum and solvent > Date: Wed, 12 May 2010 09:29:15 -0400 > > > Sent to CCL by: "Comp Chem Group " [compchemgroup1 a gmail.com] > Dear All, > By surveying on "Interaction Enthalpy" of transition metal complex in vacuum and solvent (PCM or other model), I found in all cases that the enthalpy change in vacuum is larger than that solvent. For example, if delta H in vacuum= -1000 kcal/mol, in solvent= -200 kcal/mol. Could anyone explain why? > Regards, > CCG1> > _________________________________________________________________ Hotmail: Trusted email with powerful SPAM protection. https://signup.live.com/signup.aspx?id=60969 --_b1a83c85-6f6b-43cd-97d7-4aad447bd94e_ Content-Type: text/html; charset="windows-1256" Content-Transfer-Encoding: 8bit  
People add solvent (in term of PCM) to the reactants and products; the solvation of bar metal ions releases a lot of kcal/mols at the expense of the total reaction enthalpy. If you look at the energy of solvation of the ligand, metal ion and complex, separately, you will realize this fact. I have a similar situation with a difference of about 150-300 kcal/mol between gas phase and solution, depending of your metal ion, ligand and the resulting complex.
 

 
=============================
Professor Ahmed El-Nahas
Physical Chemistry (Quantum Chemistry)
Computational Chemistry Unit (CCU)
Chemistry Department
Faculty of Science
El-Menoufia University
Shebin El-Kom
Egypt
Email: amelnahas*_*hotmail.com
Tel: +2-016-4607974; +81-09062124377
==============================



 
> From: owner-chemistry*_*ccl.net
> To: amelnahas*_*hotmail.com
> Subject: CCL: Binding Enthalpy in vacuum and solvent
> Date: Wed, 12 May 2010 09:29:15 -0400
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>
> Sent to CCL by: "Comp Chem Group " [compchemgroup1 a gmail.com]
> Dear All,
> By surveying on "Interaction Enthalpy" of transition metal complex in vacuum and solvent (PCM or other model), I found in all cases that the enthalpy change in vacuum is larger than that solvent. For example, if delta H in vacuum= -1000 kcal/mol, in solvent= -200 kcal/mol. Could anyone explain why?
> Regards,
> CCG1
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