I am in the process of revising my annual lecture to first year university students on the topic of “curly arrows”. I like to start my story in 1924, when Robert Robinson published the very first example as an illustration of why nitrosobenzene undergoes electrophilic bromination in the para position of the benzene ring.
Tom recently emailed me this question: Do you know how to find out how many of the compounds that appear in the chemical literature are mentioned just once? Intrigued, I first set out to find out how many substances, as Chemical Abstracts refers to the them, there were as of 5 June, 2025.
I thought I was done with exploring anomeric effects in small sulfur rings. However, I then realised that all the systems that I had described had an odd number of atoms and that I had not looked at any even numbered rings.
Last year I reminisced on the occasion of the 40th Anniversary of the Macintosh computer.
In this series of posts about the electronic effects in small sulfur rings I have explored increasingly large induced geometric effects.
The two previous posts, on the topic of anomeric effects in 7-membered sulfur rings illustrated how orbital interactions between the lone pairs in the molecules and S-S bonds produced widely varying S-S bond lengths in the molecules, some are shorter than normal (which is ~2.05Å for e.g. the S8 ring) by ~ 0.1Å and some […]
The monosulfoxide of cyclo-heptasulfur was reported along with cycloheptasulfur itself in 1977, along with the remarks that “The δ modification of S7 contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule.
Way back in 1977, the crystal structure of the sulfur ring S7 was reported.
Back in early 2012, I pondered about the relationships between a science-based blog post and a science-based journal article. This was in part induced by my discovering a blog plugin called Kcite, which allow a journal articles to be appended to the blog in the form of a numbered reference list.
X-ray crystallography is the technique of using the diffraction of x-rays by the electrons in a molecule to determine the positions of all the atoms in that molecule. Quantum theory teaches us that the electrons are to be found in shells around the atomic nuclei.