Posts Tagged ‘10.1021’
Monday, June 26th, 2017
About 18 months ago, there was much discussion on this blog about a system reported by Bob Pascal and co-workers containing a short H…H contact of ~1.5Å[1]. In this system, the hydrogens were both attached to Si as Si-H…H-Si and compressed together by rings. Now a new report[2] and commented upon by Steve Bachrach, claims a similar distance for hydrogens attached to carbon, i.e. C-H…H-C, but without the ring compression.
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References
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J. Zong, J.T. Mague, and R.A. Pascal, "Exceptional Steric Congestion in an in,in-Bis(hydrosilane)", Journal of the American Chemical Society, vol. 135, pp. 13235-13237, 2013. http://dx.doi.org/10.1021/ja407398w
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S. Rösel, H. Quanz, C. Logemann, J. Becker, E. Mossou, L. Cañadillas-Delgado, E. Caldeweyher, S. Grimme, and P.R. Schreiner, "London Dispersion Enables the Shortest Intermolecular Hydrocarbon H···H Contact", Journal of the American Chemical Society, vol. 139, pp. 7428-7431, 2017. http://dx.doi.org/10.1021/jacs.7b01879
Tags:10.1021, Blog, chemical shift, chemical shift difference, chemical shifts, gas phase, Interesting chemistry, Oxygen, Steve Bachrach
Posted in Uncategorised | 3 Comments »
Saturday, December 31st, 2016
My holiday reading has been Derek Lowe’s excellent Chemistry Book setting out 250 milestones in chemistry, organised by year. An entry for 1920 entitled hydrogen bonding seemed worth exploring in more detail here.
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Tags:10.1021, aqueous solution, Chemical bond, chemical bonding, Chemistry, Derek Lowe, Historical, Hydrogen, Hydrogen bond, Intermolecular forces, Lowe's, Nature, Supramolecular chemistry
Posted in Uncategorised | 2 Comments »
Wednesday, June 22nd, 2016
I previously used data mining of crystal structures to explore the directing influence of substituents on aromatic and heteroaromatic rings. Here I explore, quite literally, a different angle to the hydrogen bonding interactions between a benzene ring and OH or NH groups.
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Tags:10.1021, 10.1107, 10.5517, aromaticity, benzene, Centroid, chemical bonding, Chemical IT, data mining, Functional groups, Hydrogen bond, Physical organic chemistry, Pyridine, Simple aromatic rings, Supramolecular chemistry
Posted in crystal_structure_mining | 3 Comments »
Thursday, November 6th, 2014
Solvolytic mechanisms are amongst the oldest studied, but reproducing their characteristics using computational methods has been a challenging business. This post was inspired by reading Steve Bachrach’s post, itself alluding to this aspect in the title “Computationally handling ion pairs”. It references this recent article on the topic[1] in which the point is made that reproducing the features of both contact and solvent-separated ion pairs needs a model comprising discrete solvent molecules (in this case four dichloromethane units) along with a continuum model.
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References
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T. Hosoya, T. Takano, P. Kosma, and T. Rosenau, "Theoretical Foundation for the Presence of Oxacarbenium Ions in Chemical Glycoside Synthesis", The Journal of Organic Chemistry, vol. 79, pp. 7889-7894, 2014. http://dx.doi.org/10.1021/jo501012s
Tags:10.1021, Steve Bachrach
Posted in reaction mechanism | No Comments »
Sunday, April 28th, 2013
I recently got an email from a student asking about the best way of rationalising epoxide ring opening using some form of molecule orbitals. This reminded me of the famous experiment involving propene epoxide.[1]
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References
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H.C. Chitwood, and B.T. Freure, "The Reaction of Propylene Oxide with Alcohols", Journal of the American Chemical Society, vol. 68, pp. 680-683, 1946. http://dx.doi.org/10.1021/ja01208a047
Tags:10.1021, energy, Interesting chemistry, lowest energy, predominant product, Reaction Mechanism, Tutorial material
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Friday, April 2nd, 2010
One of the (not a few) pleasures of working in a university is the occasional opportunity that arises to give a new lecture course to students. New is not quite the correct word, since the topic I have acquired is Conformational analysis. The original course at Imperial College was delivered by Derek Barton himself about 50 years ago (for articles written by him on the topic, see DOI 10.1126/science.169.3945.539 or the original 10.1039/QR9561000044), and so I have had an opportunity to see how the topic has evolved since then, and perhaps apply some quantitative quantum mechanical interpretations unavailable to Barton himself.
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Tags:10.1021, conformational analysis, Derek Barton, energy maxima, Imperial College, Interesting chemistry, lower energy, overall energy, potential energy surface, Tutorial material
Posted in Uncategorised | 11 Comments »