From BILLINGS@UConnVM.UConn.Edu Tue Nov 15 16:26:56 1994 Received: from phem3 for BILLINGS@UConnVM.UConn.Edu by www.ccl.net (8.6.9/930601.1506) id PAA22684; Tue, 15 Nov 1994 15:51:39 -0500 Received: from UCONNVM.UCONN.EDU (MAILER@UCONNVM) by phem3.acs.ohio-state.edu (PMDF V4.2-13 #5888) id <01HJIIAYAGPC8YEEUJ@phem3.acs.ohio-state.edu>; Tue, 15 Nov 1994 15:51:35 EST Received: from UConnVM.UConn.Edu (BILLINGS) by UCONNVM.UCONN.EDU (Mailer R2.08 R208004) with BSMTP id 8931; Tue, 15 Nov 94 14:43:21 EST Date: Tue, 15 Nov 1994 14:40:19 -0500 (EST) From: Eric Billings Subject: MOPAC Cu Complex questions To: CHEMISTRY@ccl.net Message-id: <01HJIIAYAQCI8YEEUJ@phem3.acs.ohio-state.edu> Content-transfer-encoding: 7BIT Hello fellow netters: We have been using MOPAC (AM1 hamiltonian) to generate partial charges on a tetradentate dinegative ligand that has a metal binding site and a separate protonation site (an amine). The ligand has one plane of symmetry. We have used sparkles to mimic the charge polarization of the metal center since we have been unable to locate parameters for copper (I and II). /CH2-C=O + CH2-NH O H3N \ / \ / C Cu(I/II) H3C / \ / \ CH2-NH O \CH2-C=O We have two questions: 1. Are there MOPAC parameters for Cu I and II available ? 2. Can anyone help explain why MOPAC is able to converge in three of the four cases below - but fail on the fourth. We have found the following: 1. When the ++ sparkle is used, and the protonation site is protonated (-NH3+) the set of partial charges obtained reflects the symmetry of the ligand. (Total molecular charge: +1) 2. When the ++ sparkle is used, and the protonation site is unprotonated (-NH2) the set of partial charges obtained reflects the symmetry of the ligand. (Total molecular charge: 0) 3.When a + sparkle is used, and the protonation site is protonated, a set of charges is obtained which also properly reflects ligand symmetry. (Total molecular charge: 0) 4. However, when a + sparkle and no protonation is used, MOPAC cannot converge with a total molecular charge: -1. However, if CHARGE=-0.999 is used, convergence is achieved with questionable results. Specifically, the partial charges do not reflect the symmetry of the molecule. This result appears to be chemically unreasonable. In addition, the assymetry of the partial charges in (4) can be reversed simply by rotating the -NH2 group around its C-N axis. We would appreciate suggestions about any fixes for this problem, or discussion about the result. Please respond to me directly and I'll summarize if folks are interested. We've included the input file for the difficult case below. Thanks !!! - Eric Eric Billings Biophysics Grad Student UCONN Billings@uconnvm.uconn.edu ------------------------------------------------------------------- Here's the file that converges with CHARGE=-0.999 (but not -1) and produces the asymmetric charges. ------------------------------------------------------------------- GRAPH UHF CHARGE=-0.999 AM1 1SCF INSIGHT generated AMPAC/MOPAC input file DATE: Fri Nov 4 15:19:28 1994 + 0.000000 0 0.000000 0 0.000000 0 0 0 0 O 3.945394 0 0.000000 0 0.000000 0 1 0 0 N 1.988805 0 63.980175 0 0.000000 0 1 2 0 C 1.243780 0 21.286814 0 11.840311 0 2 3 1 C 2.483390 0 95.464783 0 177.089172 0 3 1 4 C 2.741488 0 155.718201 0 172.258453 0 1 3 4 O 2.069859 0 98.706131 0 -90.481331 0 1 3 4 O 1.959568 0 83.935295 0 97.237152 0 1 3 7 O 1.954638 0 172.158951 0 76.167824 0 1 3 8 O 1.222477 0 123.999367 0 178.865356 0 6 9 1 N 1.998371 0 95.456062 0 166.698486 0 1 3 8 N 1.512800 0 138.539734 0 -136.269485 0 5 3 1 C 1.476681 0 104.733261 0 -164.992844 0 3 1 11 C 1.468735 0 117.143456 0 -38.470036 0 3 1 11 C 1.529775 0 112.715981 0 -70.285004 0 5 14 3 C 1.519738 0 116.683731 0 -1.443380 0 6 9 1 C 1.516491 0 112.850174 0 59.862339 0 5 14 3 H 0.847857 0 105.924355 0 85.132477 0 3 1 11 H 0.852142 0 104.861160 0 -84.707642 0 11 1 3 H 0.971031 0 110.465836 0 -54.648548 0 12 5 14 H 0.898043 0 112.369568 0 -179.796890 0 12 5 14 H 0.939738 0 109.942955 0 74.964302 0 13 3 1 H 0.869576 0 109.047089 0 -157.552032 0 13 3 1 H 0.983221 0 107.203888 0 -61.799381 0 14 3 1 H 0.912557 0 110.428726 0 176.152573 0 14 3 1 H 0.931023 0 109.966446 0 -49.515186 0 15 5 14 H 0.900946 0 110.653557 0 -169.862305 0 15 5 14 H 0.944812 0 109.929031 0 -90.911400 0 16 11 1 H 0.881151 0 109.577477 0 148.162247 0 16 11 1 H 0.930954 0 112.317932 0 -61.163052 0 17 5 14 H 0.964762 0 109.814117 0 55.678158 0 17 5 14 H 1.001573 0 109.777176 0 175.788788 0 17 5 14 H 0.942113 0 106.874374 0 -179.980927 0 7 1 3 H 1.210611 0 104.268616 0 69.931961 0 7 1 3 -------------------------------------------------------------------