Talk:Bürgi–Dunitz angle

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I wonder if this wording is not a little misleading, since this would seem to suggest the validity of the Cram model were it not for the electronegativity of the oxygen, rather than what is meant by the text of the electronegativity of oxygen pushing the ideal angle from 109.5 to 107 degrees. Perhaps it would be better rephrased, slightly. Are there any objections? Gaedheal (talk) 23:27, 3 November 2009 (UTC)[reply]

I agree with he above post. Pi* is not at all perpindicular to the bond. I'm wondering if the author only took introductory organic chemistry. —Preceding unsigned comment added by 140.180.54.43 (talk) 22:50, 19 October 2010 (UTC)[reply]

From FMO theory the nucleophile HOMO is interacting directly with the carbonyl LUMO (the π*-orbital) so the statement that the nucleophile is "avoiding" the π*-orbital must be incorrect. However the nucleophile HOMO is minimising its interaction with the carbonyl π-orbital (note no *). Was this a typo? The B-D angle is a product of maximising the carbonyl π*-orbital interaction (attractive - maximum at 90 degrees) while simultaneously minimising the carbonyl π-orbital interaction (repulsive - minimum at 180 degrees).

"antibonding nodes of the π*-orbital of the carbonyl LUMO" - this is doubly tautological as 1) by definition an antibonding orbital only has antibonding nodes. It does not have bonding nodes so there is no distinction to be made. 2) Also a LUMO in this case is always the antibonding orbital. You can see tautology here when expanding the "LUMO" acronym - "the π*-orbital of the carbonyl Lowest Unoccupied Molecular Orbital". They are one and the same.

"atomic orbital " - the carbonyl π* and π orbitals are molecular orbitals. —Unsigned

My grammar checker chokes on this. How about: "When considering only the carbonyl π*-orbital, nucleophilic attack should be at the most electropositive end of the carbonyl bond and perpendicular to the C=O bond. However the repulsive interaction between the nucleophile HOMO and the carbonyl π-orbital (HOMO) forces the approach angle to increase to 107 degrees. The angle is a compromise between minimising the nucleophile HOMO - carbonyl HOMO interaction while maximising the nucleophile HOMO - carbonyl LUMO interaction" —Unsigned

This wiki has gone from bad (even after my early work) to worse. What needs be done is someone to simply adapt Fleming's excellent description of this and the Flippin-Lodge angle, in his student or reference edition ... then to leave it alone (apart from formatting, and updates from the literature, as needed). Thankfully, the citation for Fleming still survives all the corrections and additions. Prof D. — Preceding unsigned comment added by 67.173.94.53 (talk) 00:55, 24 May 2012 (UTC)[reply]

further relevant citations, and better wikipedia formatting. If anyone wants to undertake the latter, I would be glad to assist. If others wish to suggest references, I would be glad to try to adapt them to the article framework. Cheers. LeProf Leprof 7272 (talk)

Two editors have made changes to citation styles at this article, after original, old-fashioned citations were introduced with the writing of the article. The first set of changes were done systematically, applying a template, and resulted in no loss of information. The second set was also done, apparently using a template, but was done relatively carelessly, and resulted in overall loss of information -- page numbers, URLs to full texts of online articles, specific book edition, etc. -- as well as to the reappearance of redundancies in citations appearing.

Noteworthy also is that in neither case of template reformatting of citations were the proposed changes discussed before they were imposed.

My first concern regarding edits to citations is that they not to remove information that allows readers to learn more about the subject -- so leads to objection to carelessness that loses information like page numbers and URLs. My second concern is for the ability to conveniently edit the article, which occurs when changes are made that delete full source information that makes clear to active editors which specific article/book, and part of an article/book is being cited. (That an inline use of a citation is valid takes an instant of work to verify if the full citation information appears somewhere in the article; it takes much longer if the citation is fully removed, and replaced by a numerical link lacking any indication of the link's content, everywhere in the article.) My third - and distant third concern - is for absolute consistency of appearance/style.

Critically, the change from old-fashioned citations via the two template-driven steps has resulted in information both less accurate, complete, and useful, but also whose formats and appearance are more variable. (Some accuracy and completeness issues could be corrected, but only by returning to the original, non-templated information. Hence, as a result, we now have multiple styles appearing in the ref list. Look at where author initials appear relative to their names, in each citation, as an indication of the larger formatting issues.)

No one has time to redo work, re-adding deleted information, researching to establish that other replacements have been done correctly.This leads me to formally request, here, per WP policy, that further changes to citation style at this article only be made, with prior discussion, here in Talk. Otherwise, time constraints will simply mean that this article also will have to go by the wayside, because there is not time both to improve it, and to re-do past work that was at least sufficient.

Le Prof Leprof 7272 (talk) 14:34, 28 November 2014 (UTC)[reply]

Not sure of the proper process for this, but after reviewing what I could find of the meanings of the article classes, I changed the class from "start" to "B". Please review and keep or improve. —Unsigned