Chemical SciencesWordPress

Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
Home PageAtom Feed
language
Published

This week the ACS announced its intention to establish a “ ChemRxiv preprint server to promote early research sharing ”. This was first tried quite a few years ago, following the example of especially the physicists. As I recollect the experiment lasted about a year, attracted few submissions and even fewer of high quality.

Published

Here is a little molecule that can be said to be pretty electron rich. There are lots of lone pairs present, and not a few electron-deficient σ-bonds. I thought it might be fun to look at the stereoelectronic interactions set up in this little system.

Published

In March, I posted from the ACS meeting in San Diego on the topic of Research data: Managing spectroscopy-NMR, and noted a talk by MestreLab Research on how a tool called Mpublish in the forthcoming release of their NMR analysis software Mestrenova could help. With that release now out, the opportunity arose to test the system.

Published

The anomeric effect occurs at 4-coordinate (sp 3 ) carbon centres carrying two oxygen substituents and involves an alignment of a lone electron pair on one oxygen with the adjacent C-O σ*-bond of the other oxygen. Here I explore whether other centres can exhibit the phenomenon.

Published

I previously used data mining of crystal structures to explore the directing influence of substituents on aromatic and heteroaromatic rings. Here I explore, quite literally, a different angle to the hydrogen bonding interactions between a benzene ring and OH or NH groups. I start by defining a benzene ring with a centroid.

Published

This is a follow-up to the post on exploring the directing influence of (electron donating) substituents on benzene[cite]10.1021/acs.jchemed.5b00346[/cite] with the focus on heteroaromatic rings such indoles, pyrroles and group 16 analogues (furans, thiophenes etc). The search query is shown above (and is available here[cite]10.14469/hpc/665[/cite]). As before, the distance is compared from an electrophile, modelled as

Published

In this post, I pondered upon the C=O infra-red spectroscopic properties of esters, and showed three possible electronic influences: The red (and blue) arrows imply the C-O bond might shorten and the C=O bond would lengthen; the green the reverse. So time for a search of the crystal structure database as a reality check.