Posts Tagged ‘Bond length’

Anomeric effects at boron, silicon and phosphorus.

Friday, July 1st, 2016
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The anomeric effect occurs at 4-coordinate (sp3) 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. I start with 4-coordinate boron, using the crystal structure search definition below (along with R < 0.1, no disorder, no errors).[1]anomeric-bo-sq

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References

  1. Henry Rzepa., "Anomeric effects at boron, silicon and phosphorus.", 2016. http://dx.doi.org/10.14469/hpc/696

A wider look at π-complex metal-alkene (and alkyne) compounds.

Monday, June 13th, 2016
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Previously, I looked at the historic origins of the so-called π-complex theory of metal-alkene complexes. Here I follow this up with some data mining of the crystal structure database for such structures.

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Bond stretch isomerism. Did this idea first surface 100 years ago?

Tuesday, February 9th, 2016
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The phenomenon of bond stretch isomerism, two isomers of a compound differing predominantly in just one bond length, is one of those chemical concepts that wax and occasionally wane.[1] Here I explore such isomerism for the elements Ge, Sn and Pb.

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References

  1. J.A. Labinger, "Bond-stretch isomerism: a case study of a quiet controversy", Comptes Rendus Chimie, vol. 5, pp. 235-244, 2002. http://dx.doi.org/10.1016/S1631-0748(02)01380-2