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  2. Generating resonance structures - ChemAxon Forum Archive

    forum.chemaxon.com/6/10364/generating-resonance-structures

    Two major resonance contributors will be generated after substituting a carbon atom in the original structure with an isotop carbon. See the attached figure. Jozsi. User 2e847e51e5. 03-04-2013 14:20:22. Thanks for the answer - that works. Maybe something for a future release of the resonance plugin to be able to generate all relevant resonance ...

  3. Great! I didn't see that you could calculate resonance structures and tautomers separately. I notice that your resonance structure calculator does not include diradical resonance forms, e.g., (CH 3) 2 C•(O•). It ought to do. After all, (CH 3) 2 C•(O•) is a much more important structure than (CH 3) 2 C – (O +). Ah, now I see what you ...

  4. Wrong tertiary amide conformation - ChemAxon Forum Archive

    forum.chemaxon.com/5/4916/wrong-tertiary-amide-conformation

    Wrong tertiary amide conformation. User cb6913e244. 04-06-2009 13:25:55. Dear all, The 3D optimization of several tertiary amides with Marvin Sketch 3.2.0 led to the following observation : the carbon from the CO is hybridized sp2, the nitrogen is hybridized sp2 and the planes of these two sp2 are orthogonal. It can be found in litterature that ...

  5. ChemAxon 25dcd765a3. 19-01-2009 18:21:06. Hi, The smiles part are the same for all structure as smiles is not able to describe explicit lone pairs, but the extended part should be different. The indexes of the atoms followed by a colon character and the number of. explicit lone electron pairs are written after " lp: ".

  6. 2) The image shows also the Marvin handling of the mesomeric resonance structures R1<->R2. Here the assignment to aromaticity corresponds to the formula R2. The Marvin handling of the dipolar resonance formula R2 is different: 2a) F.e. the Huckel HMO is now able to handle the pi-system R1<->R2 exactly as one structure.

  7. OK, we will do the following modifications in 5.2: - Rename the "Reaction Arrow" group to "Arrow" group (in the insert menu) - Rename the "Two-headed Single Reaction Arrow" to "Resonance Arrow". - Rename the "Two-headed Double Reaction Arrow" to "Equilibrium Arrow". We will also rearrange the group (in the insert menu and also on the toolbar ...

  8. the problem about Hueckel calculations on the two resonance structures for enolates, discussed in another topic seems to be solved ! Now both resonance structures give the same result for the pi energy (6.2165 beta) and the same pi electon density, see screenshot. I will test it for other mesomeric pi-systems. But what are the HMO parameters?

  9. resonance and pKas - ChemAxon Forum Archive

    forum.chemaxon.com/6/8170/resonance-and-pkas

    If I look at its resonance structure, C[CH-]C(=O)OC, then C(2), the enolate C, now has a basic pKa of 25.5, and the enolate O has one of -3.7. The problem is, these two drawings represent EXACTLY the same compound. Regardless of how I draw it, I should obtain the SAME basic and acidic pKa values for every atom.

  10. logP - structural increment - ChemAxon Forum Archive

    forum.chemaxon.com/6/10978/logp-structural-increment

    Hi, The smallest value of the "H -bond" increment contribution to the logP is approx. 0.65. See the attached figure.

  11. prevent aromatization in usmiles - ChemAxon Forum Archive

    forum.chemaxon.com/5/4207/prevent-aromatization-in-usmiles

    If you use the 'u' option your molecule is aromatized. It is not possible to prevent this. If you want non-aromatic smiles just use smiles export without 'u' option. In general, it generates the same resonant structure. Andras