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.
A few years back I followed a train of thought here which ended with hexacoordinate carbon, then a hypothesis rather than a demonstrated reality. That reality was recently confirmed via a crystal structure, DOI:10.5517/CCDC.CSD.CC1M71QM. Here is a similar proposal for penta-coordinate nitrogen.
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.
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).
The Wikipedia entry on peroxydisulfate is quite short (as of today). But I suspect this article may change things..
A pyrophoric metal is one that burns spontaneously in oxygen; I came across this phenomenon as a teenager doing experiments at home.
In the previous post, I found intriguing the mechanism by which methane (CH4) inverts by transposing two of its hydrogens. Here I take a look at silane, SiH4.
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.
This is another of those posts that has morphed from an earlier one noting the death of the great chemist George Olah.
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.
A few years back, I did a post about the Pirkle reagent and the unusual π-facial hydrogen bonding structure it exhibits. For the Pirkle reagent, this bonding manifests as a close contact between the acidic OH hydrogen and the edge of a phenyl ring;