September 6th, 2015
An article entitled "Four Decades of the Chemistry of Planar Hypercoordinate Compounds"[1] was recently reviewed by Steve Bacharach on his blog, where you can also see comments. Given the recent crystallographic themes here, I thought I might try a search of the CSD (Cambridge structure database) to see whether anything interesting might emerge for tetracoordinate carbon.
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References
- L. Yang, E. Ganz, Z. Chen, Z. Wang, and P.V.R. Schleyer, "Four Decades of the Chemistry of Planar Hypercoordinate Compounds", Angewandte Chemie International Edition, vol. 54, pp. 9468-9501, 2015. https://doi.org/10.1002/anie.201410407
Tags: Angle, Cambridge, chemical bonding, Cycloalkane, Cyclopropane, HTML, HTML element, Ligand, metal, search definition, search results, search software, Steve Bacharach
Posted in Chemical IT, crystal_structure_mining | No Comments »
September 5th, 2015
The previous post explored the structural features of amides. Here I compare the analysis with that for the closely related thioamides.
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Tags: Amide, Functional groups, Thioamide
Posted in Chemical IT, crystal_structure_mining | No Comments »
September 3rd, 2015
The first conference devoted to scientific uses of Wikipedia has just finished; there was lots of fascinating stuff but here I concentrate on one report that I thought was especially interesting. To introduce it, I need first to introduce WikiData. This is part of the WikiMedia ecosystem, and one of the newest. The basic concept is really simple.
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Posted in Chemical IT | 1 Comment »
August 29th, 2015
Most visitors to London use the famous underground trains (the “tube”) or a double-decker bus to see the city (one can also use rivers and canals). So I thought, during the tourism month of August, I would show you an alternative overground circumnavigation of the city using the metaphor of benzene.
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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, Ether, Lone pair, Physical organic chemistry, Quantum chemistry, Stereochemistry, Technology/Internet
Posted in Chemical IT, crystal_structure_mining | No Comments »
August 26th, 2015
Previously, I showed how conjugation in dienes and diaryls can be visualised by inspecting bond lengths as a function of torsions. Here is another illustration, this time of the mesomeric resonance on a benzene ring induced by an electron donating substituent (an amino group) or an electron withdrawing substituent (cyano).
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Tags: chemical bonding, Chemical nomenclature, Hammett equation, Mesomeric effect, Substituent, Substitution reactions, usual search
Posted in Chemical IT, crystal_structure_mining | No Comments »
August 25th, 2015
Here is another exploration of simple chemical concepts using crystal structures. Consider a simple diene: how does the central C-C bond length respond to the torsion angle between the two C=C bonds?
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Tags: basic chemical concepts, Cambridge, Chemical bond, chemical concepts using crystal structures, Quantum chemistry
Posted in Chemical IT, crystal_structure_mining | No Comments »
August 20th, 2015
Management of research (data) outputs is a hot topic in the UK at the moment, although the topic has been rumbling for five years or more. Most research-active higher educational establishments have or are about to publish general guidelines, which predominantly take the form of aspirational targets rather than actionable examples or use-cases.‡ Because the concepts remain somewhat abstract, one can encounter questions from researchers such as “how should I go about achieving such RDM (research data management)?” I thought it might be useful for me to here summarise some key features in the form of an FAQ that can help answer that question. I will concentrate purely on the sub-set chemistry about which I know most.
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Posted in Chemical IT | 4 Comments »
August 19th, 2015
This post is prompted by the appearance of a retrospective special issue of C&E news, with what appears to be its very own Website: internet.cenmag.org. It contains articles and interviews with many interesting people, along with several variations on the historical (albeit rather USA-centric) perspectives and a time-line covers many of the key innovations (again, from a USA-perspective). Some subjects are covered in greater depth, including computational chemistry. The periodic table too gets coverage, but surprisingly that is not of Mark Winter’s WebElements, which carries the impressive 1993-2015 continuous timeline (hence 22 in the title!).
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Tags: computational chemistry, internet.cenmag.org, Mark Winter, Robert Cailliau, search.labs.datacite.org/help/examples, spin-off, the C&E news, Tim Berners-Lee, United States
Posted in Historical | No Comments »