March 4th, 2018
A bond index (BI) approximately measures the totals of the bond orders at any given atom in a molecule. Here I ponder what the maximum values might be for elements with filled valence shells.
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Tags: Atom, Chemical bond, chemical bonding, chemical properties, Chemistry, metal bond indices, Molecule, Nature, Quantum chemistry, Residential REITs, Resonance, Tennessine, Valence, Valence electron
Posted in Interesting chemistry | No Comments »
February 24th, 2018
Another post inspired by a comment on an earlier one; I had been discussing compounds of the type I.In (n=4,6) as possible candidates for hypervalency. The comment suggests the below as a similar analogue, deriving from observations made in 1989.[1]
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References
- Y. Mazaki, and K. Kobayashi, "Structure and intramolecular dynamics of bis(diisobutylselenocarbamoyl) triselenide as identified in solution by the 77Se-NMR spectroscopy", Tetrahedron Letters, vol. 30, pp. 2813-2816, 1989. https://doi.org/10.1016/s0040-4039(00)99132-9
Tags: C, chemical bonding, Chemistry, free energy, Hypervalent molecule, Matter, Molecular geometry, Nature, Nitrogen
Posted in Hypervalency | 3 Comments »
February 23rd, 2018
A little while ago I pondered allotropic bromine, or Br(Br)3. But this is a far wackier report[1] of a molecule of light.
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References
- Q. Liang, A.V. Venkatramani, S.H. Cantu, T.L. Nicholson, M.J. Gullans, A.V. Gorshkov, J.D. Thompson, C. Chin, M.D. Lukin, and V. Vuletić, "Observation of three-photon bound states in a quantum nonlinear medium", Science, vol. 359, pp. 783-786, 2018. https://doi.org/10.1126/science.aao7293
Tags: Atomic physics, Bromine, Bromine compounds, chemist, Chemistry, Halogens, Hypobromite, Oxidizing agents
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February 16th, 2018
Last year, this article[1] attracted a lot of attention as the first example of molecular helium in the form of Na2He. In fact, the helium in this species has a calculated‡ bond index of only 0.15 and it is better classified as a sodium electride with the ionisation induced by pressure and the presence of helium atoms. The helium is neither valent, nor indeed hypervalent (the meanings are in fact equivalent for this element). In a separate blog posted in 2013, I noted a cobalt carbonyl complex containing a hexacoordinate hydrogen in the form of hydride, H–. A comment appended to this blog insightfully asked about the isoelectronic complex containing He instead of H–. Here, rather belatedly, I respond to this comment!
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References
- X. Dong, A.R. Oganov, A.F. Goncharov, E. Stavrou, S. Lobanov, G. Saleh, G. Qian, Q. Zhu, C. Gatti, V.L. Deringer, R. Dronskowski, X. Zhou, V.B. Prakapenka, Z. Konôpková, I.A. Popov, A.I. Boldyrev, and H. Wang, "A stable compound of helium and sodium at high pressure", Nature Chemistry, vol. 9, pp. 440-445, 2017. https://doi.org/10.1038/nchem.2716
Tags: chemical bonding, Chemical elements, chemical shift, Chemistry, helium, Hydride, Hydrogen, Hypervalent molecule, Matter, Metal hydrides, Reducing agents, Transition metal hydride
Posted in Hypervalency | 4 Comments »
February 9th, 2018
Last year, I showed photos of wildflower meadows in west London close to where we live, evolving as the seasons changed. Today we hear the announcement that London itself is set be declared the world’s first National Park City in 2019.
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Tags: City: London, Country: United Kingdom, Royal Horticultural Society, Wildflower
Posted in Interesting chemistry | 1 Comment »
February 3rd, 2018
The topic of open citations was presented at the PIDapalooza conference and represents a third component in the increasing corpus of open scientific information.
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Tags: Academic publishing, Applied linguistics, article processing charge, British National Corpus, chemical stories, cited author, Corpus linguistics, David Shotton, Entertainment/Culture, Linguistics, Open access, Quotation, RDF, social media, Texas A&M–Corpus Christi Islanders women's basketball
Posted in Chemical IT | 2 Comments »
January 23rd, 2018
Another occasional conference report (day 1). So why is one about “persistent identifiers” important, and particularly to the chemistry domain?
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Tags: Academic publishing, Andy Mabbett, Digital Object Identifier, Identifiers, Imperial College, Index, Information science, Johanna McEntyre, Knowledge, Mark Hahnel, ORCiD, Persistent identifier, Publishing, Quotation, researcher, Scholarly communication, SciCrunch, search engines, Technical communication, Technology/Internet, Tom Gillespie
Posted in Chemical IT | 1 Comment »
January 14th, 2018
I don’t normally write about the pharmaceutical industry, but I was intrigued by several posts by Derek Lowe (who does cover this area) on the topic of creating new drugs by deuterating existing ones. Thus he covered the first deuterated drug receiving FDA approval last year, having first reviewed the concept back in 2009. So when someone introduced me to sila-haloperidol, I checked to see if Derek had written about it. Apparently not, so here are a few details.
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Tags: Chemistry, Derek Lowe, Deuterated drug, Drug, drug design, FDA, Food and Drug Administration, Haloperidol, Health, Health/Medical/Pharmaceuticals, HTC HD2 Smartphone, metabolic products, Pharmaceutical industry, Pharmacy, physico-chemical profiles, United States Public Health Service
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January 13th, 2018
I discussed the molecule the molecule CH3F2- a while back. It was a very rare computed example of a system where the added two electrons populate the higher valence shells known as Rydberg orbitals as an alternative to populating the C-F antibonding σ-orbital to produce CH3– and F–. The net result was the creation of a weak C-F “hyperbond”, in which the C-F region has an inner conventional bond, with an outer “sheath” encircling the first bond. But this system very easily dissociates to CH3– and F– and is hardly a viable candidate for experimental detection. In an effort to “tune” this effect to see if a better candidate for such detection might be found, I tried CMe3F2-. Here is its story.
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Tags: Antibonding molecular orbital, candidate for experimental detection, chemical bonding, chemical shift, Chemistry, metal, Molecular orbital, Nature
Posted in Hypervalency | 2 Comments »
January 6th, 2018
The title here is from an article on metalenses[1] which caught my eye.
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References
- M. Khorasaninejad, W.T. Chen, A.Y. Zhu, J. Oh, R.C. Devlin, D. Rousso, and F. Capasso, "Multispectral Chiral Imaging with a Metalens", Nano Letters, vol. 16, pp. 4595-4600, 2016. https://doi.org/10.1021/acs.nanolett.6b01897
Tags: Biochemistry, Biology, Chemistry, Chirality, Circular dichroism, Nature, Pharmacology, Polarization, spectroscopy, Stereochemistry, Ultraviolet, Vibrational circular dichroism
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