From chemistry-request@www.ccl.net Mon Aug 24 02:40:08 1998 Received: from mx03.uni-tuebingen.de (root@mx03.uni-tuebingen.de [134.2.3.13]) by www.ccl.net (8.8.3/8.8.6/OSC/CCL 1.0) with ESMTP id CAA08868 Mon, 24 Aug 1998 02:40:07 -0400 (EDT) Received: from poseidon.pharm.chemie.uni-tuebingen.de (poseidon.pharm.chemie.uni-tuebingen.de [134.2.68.21]) by mx03.uni-tuebingen.de (8.8.8/8.8.8) with SMTP id IAA02883 for ; Mon, 24 Aug 1998 08:40:02 +0200 Date: Mon, 24 Aug 1998 08:40:02 +0200 Message-Id: <199808240640.IAA02883@mx03.uni-tuebingen.de> X-Sender: cpcmu01@cpcmu01.mail.uni-tuebingen.de X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: chemistry@www.ccl.net From: Inge Muszynski Subject: lone-pair-orientation in Furan Dear CCL'lers, I have got a question concerning the lone-pair-orientation of the oxygen in Furan or in other 5-cycled heteroaromatic systems like 1,3,4-Thiadiazol etc. Due to the planar character of Furan I would suppose a sp2-hybridisation for the oxygen and an in-plane-orientation for its lone-pair. Surprisingly I have found an 0sp3 for Furan in the fragmental library of my molecular modelling software SYBYL. How to think about this? Many thanks in advance. Inge Muszynski Pharmaceutical Chemistry University of Tuebingen Auf der Morgenstelle 8 72076 Tuebingen