“This molecule is very exceptional,” says Malischewski. Though scientists have found other exceptions to carbon’s four-bond limit, this is the first time carbon has been shown associating with this many other carbon atoms.
When Malischewski measured the length of the molecule’s chemical bonds, the top carbon’s six bonds were each a bit longer than an ordinary carbon-carbon bond. A longer bond is generally less strong. So by picking more partners, that carbon has a slightly weaker connection to each one.
“The carbon isn’t making six bonds in the sense that we usually think of a carbon-carbon bond as a two-electron bond,” Tantillo says. That’s because the carbon atom still has only four electrons to share. As a result, it spreads itself a bit thin by sharing electrons among the six bonds.