Is (hν)3 an allotrope of light?

February 23rd, 2018
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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

  1. 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. http://dx.doi.org/10.1126/science.aao7293

Hypervalent Helium – not!

February 16th, 2018
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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

  1. 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. http://dx.doi.org/10.1038/nchem.2716

London: set to become a National Park City in 2019.

February 9th, 2018
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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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First, Open Access, then Open (and FAIR) Data, now Open Citations.

February 3rd, 2018
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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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PIDapalooza 2018. A conference like no other!

January 23rd, 2018
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Another occasional conference report (day 1). So why is one about “persistent identifiers” important, and particularly to the chemistry domain?

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Silicon drug analogues.

January 14th, 2018
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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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Hypervalent hydrogen?

January 13th, 2018
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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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Multispectral Chiral Imaging with a Metalens.

January 6th, 2018
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The title here is from an article on metalenses[1] which caught my eye.

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References

  1. 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. http://dx.doi.org/10.1021/acs.nanolett.6b01897

Are diazomethanes hypervalent molecules? An attempt into more insight by more “tuning” with substituents.

December 26th, 2017
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Recollect the suggestion that diazomethane has hypervalent character[1]. When I looked into this, I came to the conclusion that it probably was mildly hypervalent, but on carbon and not nitrogen. Here I try some variations with substituents to see what light if any this casts.

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References

  1. M.C. Durrant, "A quantitative definition of hypervalency", Chemical Science, vol. 6, pp. 6614-6623, 2015. http://dx.doi.org/10.1039/C5SC02076J

Can any hypervalence in diazomethanes be amplified?

December 23rd, 2017
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In the previous post, I referred to a recently published review on hypervalency[1] which introduced a very simple way (the valence electron equivalent γ) of quantifying the effect. Diazomethane was cited as one example of a small molecule exhibiting hypervalency (on nitrogen) by this measure. Here I explore the effect of substituting diazomethane with cyano and nitro groups.

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References

  1. M.C. Durrant, "A quantitative definition of hypervalency", Chemical Science, vol. 6, pp. 6614-6623, 2015. http://dx.doi.org/10.1039/C5SC02076J