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Sent to CCL by: Szabolcs Csepregi [scsepregi**chemaxon.com]
Hi Johannes, The Geometry plugin from the Marvin calculator plugin collection can calculate atomic steric hindrance. See: http://www.chemaxon.com/product/geometry.html You can try it from Marvin GUI, even online from the applet: http://www.chemaxon.com/marvin/sketch/index.jsp Alternatively, the chemaxon academic package offers free licenses for batch calculation, etc. as well. I hope this helps. Best regards, Szabolcs
Szabolcs
Csepregi, PhD
Dir. of Search Technologies and Markush
project
ChemAxon Ltd. Maramaros koz 3/A, Budapest, 1037 Hungary http://www.chemaxon.com Tel: +36 1 4532661 Cell: +36 20 4219863 Fax: +36 1 4532659 Skype: szabolcs.csepregi Schwobel, Johannes J.Schwobel%x%ljmu.ac.uk wrote: Sent to CCL by: "Schwobel, Johannes" [J.Schwobel/./ljmu.ac.uk] Dear CCLers, I would appreciate your advice on two questions: I'm calculating reactivity and transition states (TS) for the Michael addition reaction (soft nucleophiles with alpha,beta unsaturated compounds) at B3LYP level. Obviously, it seems to be very difficult to locate a TS. Does anyone have any experience with theoretical TS calculations of this type of reaction or know any further papers about that? If there is a substituent in alpha-position, reactivity decreases significantly. This might have electronic or steric effects. For the latter I want to know: Is there any descriptor or parameter available to quantify the local (e.g. atom-centered) steric hindrance? Thanks a lot in advance! Johannes Schwobel -=his is automatically added to each message by the mailing script =-E-mail to subscribers: CHEMISTRY^ccl.net or use: http://www.ccl.net/cgi-bin/ccl/send_ccl_message E-mail to administrators: CHEMISTRY-REQUEST^ccl.net or use http://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtml Before posting, check wait time at: http://www.ccl.net Job: http://www.ccl.net/jobs Conferences: http://server.ccl.net/chemistry/announcements/conferences/ Search Messages: http://www.ccl.net/chemistry/searchccl/index.shtmlhttp://www.ccl.net/spammers.txt RTFI: http://www.ccl.net/chemistry/aboutccl/instructions/ |