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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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GeneralChimieAnglais
Publié

Most visitors to London use the famous underground trains (the “tube”) or a* double-decker bus* to see the city (one can also use rivers and canals). So I thought, during the tourism month of August, I would show you an alternative overground circumnavigation of the city using the metaphor of benzene. Benzene you see is a ring, comprising three “HCCH” segments.

Chemical ITCrystal_structure_miningAlkane StereochemistryAnomeric EffectCarbohydrate ChemistryChimieAnglais
Publié

The anomeric effect is best known in sugars, occuring in sub-structures such as RO-C-OR. Its origins relate to how the lone pairs on each oxygen atom align with the adjacent C-O bonds. When the alignment is 180°, one oxygen lone pair can donate into the C-O σ* empty orbital and a stabilisation occurs. Here I explore whether crystal structures reflect this effect.

Chemical ITGeneral10.15200143871.12809AcademiaChimieAnglais
Publié

I recently received two emails each with a subject line new approaches to research reporting . The traditional 350 year-old model of the (scientific) journal is undergoing upheavals at the moment with the introduction of APCs (article processing charges), a refereeing crisis and much more. Some argue that brand new thinking is now required.

Chemical ITCrystal_structure_miningInteresting ChemistryCarbonCationsChimieAnglais
Publié

I recently followed this bloggers trail; link1 → link2 to arrive at this delightful short commentary on atom-atom bonds in crystals[cite]10.1107/S2052252515002006[/cite] by Jack Dunitz. Here he discusses that age-old question (to chemists), what is a bond? Even almost 100 years after Gilbert Lewis’ famous analysis,[cite]10.1021/ja02261a002[/cite] we continue to ponder this question.

HistoricalNaphthaleneOscillationChimieAnglais
Publié

This is a little historical essay into the electronic structure of naphthalene, presented as key dates (and also collects comments made which were appended to other posts). 1890[cite]10.1039/pl8900600095[/cite]: Henry Armstrong presents the following structure of naphthalene. Three words need translation into modern usage.

Reaction MechanismActivation Free EnergyBasis SetDan SingletonEnergy DifferencesChimieAnglais
Publié

Previously on the kinetic isotope effects for the Baeyer-Villiger reaction, I was discussing whether a realistic computed model could be constructed for the mechanism. The measured KIE or kinetic isotope effects (along with the approximate rate of the reaction) were to be our reality check.

Interesting ChemistryChimieAnglais
Publié

Peter Edwards has just given the 2015 Hofmann lecture here at Imperial on the topic of solvated electrons . An organic chemist knows this species as “ e ” and it occurs in ionic compounds known as electrides ; chloride = the negative anion of a chlorine atom, hence electride = the negative anion of an electron.