Posts Tagged ‘Quantum chemistry’
Monday, August 8th, 2016
The previous post contained an exploration of the anomeric effect as it occurs at an atom centre X for which the effect is manifest in crystal structures. Here I quantify the effect, by selecting the test molecule MeO-X-OMe, where X is of two types:
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Tags:Anomer, Anomeric effect, Atomic orbital, Carbohydrate chemistry, Carbohydrates, Chemical bond, chemical bonding, Chemistry, Hydrogen bond, interaction energy, Interesting chemistry, Lone pair, Physical organic chemistry, Quantum chemistry
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Sunday, January 31st, 2016
Six years ago, I posted on the nature of a then recently reported[1] Cr-Cr quintuple bond. The topic resurfaced as part of the discussion on a more recent post on NSF3, and a sub-topic on the nature of the higher order bonding in C2. The comment made a connection between that discussion and the Cr-Cr bond alluded to above. I responded briefly to that comment, but because I want to include 3D rotatable surfaces, I expand the discussion here and not in the comment.‡
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References
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C. Hsu, J. Yu, C. Yen, G. Lee, Y. Wang, and Y. Tsai, "Quintuply‐Bonded Dichromium(I) Complexes Featuring Metal–Metal Bond Lengths of 1.74 Å", Angewandte Chemie International Edition, vol. 47, pp. 9933-9936, 2008. http://dx.doi.org/10.1002/anie.200803859
Tags:Chemical bond, chemical bonding, Electron, Electron configuration, energy, General, Interesting chemistry, Molecular orbital, Multi-configurational self-consistent field, Quantum chemistry, quintuple bond, search term, Transition metal, Valence bond theory
Posted in Uncategorised | 6 Comments »
Saturday, January 16th, 2016
The post on applying VSEPR ("valence shell electron pair repulsion") theory to the geometry of ClF3 has proved perennially popular. So here is a follow-up on another little molecue, F3SN. As the name implies, it is often represented with an S≡N bond. Here I take a look at the conventional analysis.
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Tags:Chemical bond, chemical bonding, Electron, Hypervalency, Lone pair, Molecular geometry, Octet rule, Quantum chemistry, Stereochemistry, Tetrahedral molecular geometry, Theoretical chemistry, Valence, VSEPR theory
Posted in Uncategorised | 110 Comments »
Thursday, August 27th, 2015
The anomeric effect is best known in sugars, occuring in sub-structures such as RO-C-OR. Its origins relate to how the lone pairs on each oxygen atom align with the adjacent C-O bonds. When the alignment is 180°, one oxygen lone pair can donate into the C-O σ* empty orbital and a stabilisation occurs. Here I explore whether crystal structures reflect this effect.
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Tags:Alkane stereochemistry, Anomeric effect, Carbohydrate chemistry, Carbohydrates, Carbon–oxygen bond, Chemical bond, Chemical IT, Ether, Lone pair, Physical organic chemistry, Quantum chemistry, Stereochemistry, Technology/Internet
Posted in crystal_structure_mining | No Comments »