From owner-chemistry@ccl.net Thu Jun 30 09:53:00 2022 From: "=?utf-8?B?TWFyaXVzeiBSYWRvxYQ=?= mariusz.radon_+_uj.edu.pl" To: CCL Subject: CCL: Chemical reaction insights resulting from geometry optimizations Message-Id: <-54741-220630051506-30597-1uz/jOJurGVF/2q5chEdgQ(-)server.ccl.net> X-Original-From: =?utf-8?B?TWFyaXVzeiBSYWRvxYQ=?= Content-ID: Content-Language: en-US Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" Date: Thu, 30 Jun 2022 09:14:56 +0000 MIME-Version: 1.0 Sent to CCL by: =?utf-8?B?TWFyaXVzeiBSYWRvxYQ=?= [mariusz.radon-x-uj.edu.pl] Dear Gary: Marcel Swart already gave you a fairly extensive answer, but just a small addition. I don’t have any experience with these particular reactions, but as these reactions are taking place in solution(?), have you tested the impact of solvation model (like PCM or COSMO) on the results of your geometry optimizations? There can be potentially large solvation effects for the leaving groups with anionic character. The solvation may also affect the geometries of your stationary points (which means that the geometries optimized in gas phase can be unrealistic). Best wishes, Mariusz -- Mariusz Radon, Ph.D., D.Sc. Associate Professor Faculty of Chemistry, Jagiellonian University Address: Gronostajowa 2, 30-387 Krakow, Poland Room C1-06, Phone: 48-12-686-24-89 E-mail: mradon:-:chemia.uj.edu.pl (mariusz.radon:-:uj.edu.pl) Web: https://tungsten.ch.uj.edu.pl/~mradon ORCID: https://orcid.org/0000-0002-1901-8521 > On 29 Jun 2022, at 14:51, Gary Breton gbreton:_:berry.edu wrote: > > > Sent to CCL by: "Gary Breton" [gbreton]^[berry.edu] > Hi everyone, > > There is a long history of computational modeling of elimination reactions that occur via the E2 and E1cb reaction mechanisms. The E2 mechanism is a concerted mechanism in which a base removes a beta-hydrogen atom while a leaving group (e.g., a halogen) departs more-or-less simultaneously to give rise to an alkene product. In the 2-step E1cb mechanism, the base removes the beta-hydrogen completely, and the resulting anion then "ejects" the leaving group to form the alkene product. > > While I am still perusing some of the earlier literature, I was surprised to find that no one has reported that attempts at modeling the anion "intermediate" in the E1cb route (devoid of the base and detached proton) using DFT methods (which have been the preferred methods in the literature for modeling these reactions [I am using wB97XD/aug-cc-pvtz]), results in spontaneous ejection of the leaving group during the optimization process to form the alkene. Thus, the bare anion is not a stationary point on the PES. Some competitions can be set up comparing preference for leaving group loss, etc. that appear to mirror experimental results. I'm still working on some of these interesting findings. > > Two questions: > > 1. Since I am not dealing with stationary points, how legitimate is it to compare, for example, the preference for ejection of a Cl- leaving group over a F- leaving group from a modeled (non-optimized) anion? NBO calculations have been employed that support why elimination of the Cl is preferred. > > 2. I have been trying to find other instances where attempted geometry optimizations of this sort have lead to chemical reaction insights due to spontaneous "reactivity" during the optimization process (e.g., rearrangements, eliminations, etc.). My searches have come up empty so far and was hoping some of you might lead me in the proper direction. > > Thanks for reading and any suggestions that may be offered. > > Gary Breton > Berry College> > From owner-chemistry@ccl.net Thu Jun 30 17:39:01 2022 From: "Caio Lima Firme firme.caio a gmail.com" To: CCL Subject: CCL: New book about quantum mechanics Message-Id: <-54742-220630173708-17170-HZHMHsY6NHAH+/AI/td7DQ- -server.ccl.net> X-Original-From: "Caio Lima Firme" Date: Thu, 30 Jun 2022 17:37:07 -0400 Sent to CCL by: "Caio Lima Firme" [firme.caio(-)gmail.com] Dear CCLers, I am pleased to announce the release of my new book about Quantum Mechanics - Detailed Historical, Mathematical and Computational Approaches. See the link below for more information. Link: https://www.routledge.com/Quantum-Mechanics-Detailed-Historical- Mathematical-and-Computational-Approaches/Firme/p/book/9780367506339 All the best Prof. Dr. Caio Lima Firme From owner-chemistry@ccl.net Thu Jun 30 19:03:00 2022 From: "Dorine Vidal dvidal++chemcomp.com" To: CCL Subject: CCL: CCG releases MOE 2022.02 Message-Id: <-54743-220630154828-7434-oHIyc6HhGLZaiQ9YcCPTqQ^^^server.ccl.net> X-Original-From: "Dorine Vidal" Date: Thu, 30 Jun 2022 15:48:27 -0400 Sent to CCL by: "Dorine Vidal" [dvidal^_^chemcomp.com] We are pleased to announce the 2022 release of the Molecular Operating Environment (MOE). 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