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.
Multispectral Chiral Imaging with a Metalens.
January 6th, 2018The title here is from an article on metalenses[cite]10.1021/acs.nanolett.6b01897[/cite] which caught my eye.
Are diazomethanes hypervalent molecules? An attempt into more insight by more “tuning” with substituents.
December 26th, 2017Recollect the suggestion that diazomethane has hypervalent character[cite]10.1039/C5SC02076J[/cite]. 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.
Can any hypervalence in diazomethanes be amplified?
December 23rd, 2017In the previous post, I referred to a recently published review on hypervalency[cite]10.1039/C5SC02076J[/cite] 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.‡
Are diazomethanes hypervalent molecules? Probably, but in an unexpected way!
December 23rd, 2017A recently published review on hypervalency[cite]10.1039/C5SC02076J[/cite] introduced a very simple way of quantifying the effect. One of the molecules which was suggested to be hypervalent using this method was diazomethane. Here I take a closer look.
Ammonide: an alkalide formed from ammonia and resembling an electride.
December 17th, 2017Alkalides are anionic alkali compounds containing e.g. sodide (Na–), kalide (K–), rubidide (Rb–) or caeside (Cs–). Around 90 examples can be found in the Cambridge structure database (see DOI: 10.14469/hpc/3453 for the search query and results). So what about the ammonium analogue, ammonide (NH4–)? A quick search of Scifinder drew a blank! So here I take a look at this intriguingly simple little molecule.‡
Identification of a simplest hypervalent hydrogen fluoride anion.
December 8th, 2017An article with the title shown above in part recently appeared.[cite]10.1038/s41598-017-02687-z[/cite] Given the apparent similarity of HF1- to CH3F1- and CH3F2-, the latter of which I introduced on this blog previously, I thought it of interest to apply my analysis to HF1-.
A form of life that can stably store genetic information using a six-letter, three-base-pair alphabet?
December 2nd, 2017For around 16 years, Floyd Romesberg’s group has been exploring un-natural alternatives (UBPs) to the Watson-Crick base pairs (C-G and A-T) that form part of the genetic code in DNA. Recently they have had remarkable success with one such base pair, called X and Y (for the press) and dNaMTP and d5SICSTP (in scholarly articles).[cite]10.1073/pnas.1708259114[/cite],[cite]10.1073/pnas.1205176109[/cite] This extends the genetic coding from the standard 20 amino acids to the possibility of up to 172 amino acids. Already, organisms engineered to contain X-Y pairs in their DNA have been shown to express entirely new (and un-natural) proteins.
Octet expansion and hypervalence in dimethylidyne-λ6-sulfane.
November 28th, 2017I started this story by looking at octet expansion and hypervalence in non-polar hypercoordinate species such as S(-CH3)6, then moved on to S(=CH2)3. Finally now its the turn of S(≡CH)2.‡