Posts Tagged ‘Reducing agents’
Friday, 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
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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
Tags:chemical bonding, Chemical elements, chemical shift, Chemistry, helium, Hydride, Hydrogen, Hypervalency, Hypervalent molecule, Matter, Metal hydrides, Reducing agents, Transition metal hydride
Posted in Uncategorised | 4 Comments »
Sunday, March 19th, 2017
A pyrophoric metal is one that burns spontaneously in oxygen; I came across this phenomenon as a teenager doing experiments at home. Pyrophoric iron for example is prepared by heating anhydrous iron (II) oxalate in a sealed test tube (i.e. to 600° or higher). When the tube is broken open and the contents released, a shower of sparks forms. Not all metals do this; early group metals such as calcium undergo a different reaction releasing carbon monoxide and forming calcium carbonate and not the metal itself. Here as a prelude to the pyrophoric reaction proper, I take a look at this alternative mechanism using calculations.
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Tags:Aluminium, calculated free energy barrier, Carbon monoxide, Chemical elements, Chemistry, higher activation energy, Iron, Matter, metal, metal oxalates, Oxide, pyrophoric metal, Pyrophoricity, Reducing agents
Posted in crystal_structure_mining, reaction mechanism | 1 Comment »
Friday, April 15th, 2016
In the previous post I described how hydronium hydroxide or H3O+…HO–, an intermolecular tautomer of water, has recently been observed captured inside an organic cage[1] and how the free-standing species in water can be captured computationally with the help of solvating water bridges. Here I explore azane oxide or H3N+-O–,‡ a tautomer of the better known hydroxylamine (H2N-OH).
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References
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M. Stapf, W. Seichter, and M. Mazik, "Unique Hydrogen‐Bonded Complex of Hydronium and Hydroxide Ions", Chemistry – A European Journal, vol. 21, pp. 6350-6354, 2015. http://dx.doi.org/10.1002/chem.201406383
Tags:Ammonia, aqueous solutions, Bases, energy relative, free energy, Functional groups, General, Hydrogen bond, Hydronium, Hydroxides, Hydroxyl, Hydroxylamine, Interesting chemistry, lowest energy form, Properties of water, Reducing agents, Self-ionization of water
Posted in Uncategorised | No Comments »