Henry Rzepa's Blog Chemistry with a twist

February 24, 2018

Hypervalent or not? A fluxional triselenide.

Another post inspired by a comment on an earlier one; I had been discussing compounds of the type I.In (n=4,6) as possible candidates for hypervalency. The comment suggests the below as a similar analogue, deriving from observations made in 1989.[1]



  1. Y. Mazaki, and K. Kobayashi, "Structure and intramolecular dynamics of bis(diisobutylselenocarbamoyl) triselenide as identified in solution by the 77Se-NMR spectroscopy", Tetrahedron Letters, vol. 30, pp. 2813-2816, 1989. http://dx.doi.org/10.1016/S0040-4039(00)99132-9

December 17, 2017

Ammonide: an alkalide formed from ammonia and resembling an electride.

Alkalides are anionic alkali compounds containing e.g. sodide (Na), kalide (K), rubidide (Rb) or caeside (Cs). Around 90 examples can be found in the Cambridge structure database (see DOI: 10.14469/hpc/3453  for the search query and results). So what about the ammonium analogue, ammonide (NH4)? A quick search of Scifinder drew a blank! So here I take a look at this intriguingly simple little molecule.


March 25, 2017

First, hexacoordinate carbon – now pentacoordinate oxygen?

Filed under: Bond slam,Hypervalency — Tags: , , , , , — Henry Rzepa @ 5:28 pm

The previous post demonstrated the simple iso-electronic progression from six-coordinate carbon to five coordinate nitrogen. Here, a further progression to oxygen is investigated computationally.


July 8, 2016

Anomeric effects at carbon involving lone pairs originating from one or two nitrogens.

The previous post looked at anomeric effects set up on centres such as B, Si or P, and involving two oxygen groups attached to these atoms. Here I vary the attached groups to include either one or two nitrogen atoms.[1]



  1. Henry Rzepa., "Anomeric effects at carbon, involving lone pairs originating from one or two nitrogens", 2016. http://dx.doi.org/10.14469/hpc/936

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