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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Chemical ITCrystal_structure_miningAlkane StereochemistryAnomeric EffectCarbohydrate ChemistryChemical Sciences
Published

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.

Chemical ITCrystal_structure_miningChemical BondingChemical NomenclatureHammett EquationChemical Sciences
Published

Previously, I showed how conjugation in dienes and diaryls can be visualised by inspecting bond lengths as a function of torsions. Here is another illustration, this time of the mesomeric resonance on a benzene ring induced by an electron donating substituent (an amino group) or an electron withdrawing substituent (cyano).

Chemical ITGeneral10.15200143871.12809AcademiaChemical Sciences
Published

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 ChemistryCarbonCationsChemical Sciences
Published

I recently followed this bloggers trail; link1 → link2 to arrive at this delightful short commentary on atom-atom bonds in crystals 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, we continue to ponder this question.