March 18th, 2018
I have posted often on the chemical phenomenon known as hypervalency, being careful to state that as defined it applies just to “octet excess” in main group elements. But what about the next valence shell, occurring in transition metals and known as the “18-electron rule”? You rarely hear the term hypervalency being applied to such molecules, defined presumably by the 18-electron valence shell count being exceeded. So the following molecule (drawn in three possible valence bond representations) first made in 1992 intrigues.[cite]10.1002/anie.199203231[/cite]
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Posted in Hypervalency | 3 Comments »
March 7th, 2018
C&EN has again run a vote for the 2017 Molecules of the year. Here I take a look not just at these molecules, but at how FAIR (Findable, Accessible, Interoperable and Reusable) the data associated with these molecules actually is.
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Tags: Carotenoids, Chemistry, Epoxides, Macrocycles, Organic chemistry, Organofluorides, PDF, Peptides, search engine, search program, search.datacite.org search engine, Technology/Internet
Posted in Chemical IT, crystal_structure_mining, Interesting chemistry | No Comments »
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.[cite]10.1016/S0040-4039(00)99132-9[/cite]
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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[cite]10.1126/science.aao7293[/cite] of a molecule of light.
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Tags: Atomic physics, Bromine, Bromine compounds, chemist, Chemistry, Halogens, Hypobromite, Oxidizing agents
Posted in Interesting chemistry | No Comments »
February 16th, 2018
Last year, this article[cite]10.1038/nchem.2716[/cite] 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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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
Posted in General | No Comments »