From chemistry-request -A_T- www.ccl.net Tue Sep 15 10:22:03 1998 Received: from crusher.cc.manhattan.edu (crusher.cc.manhattan.edu [149.61.10.20]) by www.ccl.net (8.8.3/8.8.6/OSC/CCL 1.0) with ESMTP id KAA19039 Tue, 15 Sep 1998 10:22:02 -0400 (EDT) Received: from europa.mc.manhattan.edu (europa.mc.manhattan.edu [149.61.74.6]) by crusher.cc.manhattan.edu (AIX4.2/UCB 8.7/8.7) with ESMTP id KAA22162 for ; Tue, 15 Sep 1998 10:00:03 -0400 (EDT) Received: from EUROPA/SpoolDir by europa.mc.manhattan.edu (Mercury 1.43); 15 Sep 98 10:16:12 -0500 Received: from SpoolDir by EUROPA (Mercury 1.43); 15 Sep 98 10:15:49 -0500 From: "Joseph Capitani" Organization: Manhattan College, Riverdale N.Y. To: chemistry-!at!-www.ccl.net Date: Tue, 15 Sep 1998 10:15:41 EST5EDT Subject: Allowed Spin Multiplicity of Transition States X-Confirm-Reading-To: "Joseph Capitani" X-pmrqc: 1 Priority: normal X-mailer: Pegasus Mail for Windows (v2.52) Message-ID: <1C36121727D(+ at +)europa.mc.manhattan.edu> Hello, We have been trying to calculate transition state energies and geometries for reactions that can be be summarized as AB + CD -----> { A---B---C---D} ----> AC + BD. AB is a known singlet, CD is a known triplet, AC is a known singlet and BD is a triplet. {A--B--C---D} is the T.S. and the reaction is not photochemical. My questions are: 1. What is/are the allowed spin(s) of the transition state? Are there general rules that govern the choice(s)? 2. Given the spin multiplicities of the reactants, are there general rules which fix the spins of the individual products? Any information would be greatly appreciated! Thanks, Joe Capitani