A High school student from Oklahoma has just discovered something completely unexpected in chemistry. He found out that carbon, which usually only forms four bonds, can end up forming a mind-boggling seven bonds, a higher number than ever considered possible for the element.
High school chemistry tells us all about the versatility of carbon. You might recall that carbon is missing four electrons in its outer shell so it's looking to form up to four bonds. Having this ability makes it very useful as the basis for anything biological. These four bonds are found in so many important molecules, from DNA to alcohol to diamonds. But that’s not the whole story.
There are exceptions, situations in which carbon can do more than four bonds. The element in those cases is nicknamed hypercarbon. In the 1950s, it was shown that carbon can sometimes form five bonds. And in 2016, a German team showed how to make a six-bond hypercarbon. This paper was the start of this discovery. Dr AK Fazlur Rahman was giving a lecture on carbon at Oklahoma School of Science and Mathematics in Oklahoma City. He used the 2016 paper to challenge his students on thinking about the possibility of carbon with more than six bonds. Unexpectedly, one of his students, George Wang, did more than just imagine it. He showed that six was not a strict limit. It was possible to have a carbon with seven bonds.
As reported in Inverse, Dr Rahman asked to see Mr Wang's calculations and not only did it show the stability of the seven-bond configuration of carbon and hydrogen, It also showed that an eight-bond version with just the same two elements would be unstable. These calculations are now published in the Journal of Molecular Modeling.
The team showed that it is possible to construct a pyramid shape made of carbon atoms. The base would be a hexagonal carbon ring and the vertex would connect with all six of these carbons. Since every carbon would also link to a hydrogen atom it ends up that the vertex carbon has seven bonds.
Molecules sporting hypercarbon atoms are extremely unusual compounds, so this could turn out to be revolutionary. Such structures could lead to a completely new approach to organic chemistry. Hydrogen storage is a potential application. New avenues for chemical synthesis are also possibilities mentioned in the paper. Exciting stuff.