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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Crystal_structure_mining2-Norbornyl CationCarbocationsChemical BondingChemistryChemieEnglisch
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It is not only the non-classical norbornyl cation that has proved controversial in the past. A colleague mentioned at lunch (thanks Paul!) that tri-coordinate group 14 cations such as R3Si+ have also had an interesting history. Here I take a brief look at some of these systems.

Reaction MechanismAnimationChemical ReactionChemistryComputational ChemistryChemieEnglisch
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The example a few posts back of how methane might invert its configuration by transposing two hydrogen atoms illustrated the reaction mechanism by locating a transition state and following it down in energy using an intrinsic reaction coordinate (IRC). Here I explore an alternative method based instead on computing a molecular dynamics trajectory (MD).

Reaction MechanismChemistryMethaneMolecular GeometryOrbital HybridisationChemieEnglisch
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This is a spin-off from the table I constructed here for further chemical examples of the classical/non-classical norbornyl cation conundrum. One possible entry would include the transition state for inversion of methane via a square planar geometry as compared with e.g. NiH4 for which the square planar motif is its minimum.

Interesting Chemistry2-Norbornyl CationAqueous SolutionsChemical BondChemical InstrumentationChemieEnglisch
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George Olah passed away on March 8th. He was part of the generation of scientists in the post-war 1950s who had access to chemical instrumentation that truly revolutionised chemistry.

Chemical ITAPIChemical DatabasesCity: LondonCompany: TfLChemieEnglisch
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Living in London, travelling using public transport is often the best way to get around. Before setting out on a journey one checks the status of the network. Doing so today I came across this page: our open data from Transport for London.

Crystal_structure_miningAntiaromaticityChemistryCyclobutadieneInstabilityChemieEnglisch
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Cyclobutadiene is one of those small iconic molecules, the transience and instability of which was explained theoretically long before it was actually detected in 1965. Given that instability, I was intrigued as to how many crystal structures might have been reported for this ring system, along with the rather more stable congener cyclo-octatetraene.