Carbon Found To Form More Than 4 Bonds

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One of the fundamental principles of organic chemistry is that a carbon atom has 4 electrons in the outer shell allowing it to form a maximum of 4 bonds. But a team of researchers revisiting an experiment from the 1970s has found an exception to that rule. Carbon has been now shown to form six bonds under particular conditions.

According to Science News, in the 1970s, German scientists discovered an unusual molecule called Hexamethylbenzene or HMB. Its structure consists of a hexagonal ring with one arm sticking out of each vertex of the hexagon. Every arm has 1 carbon atom bonded to 3 other hydrogen atoms.

The scientists removed two electrons from the molecule. A drastic change in shape was expected but the result was unexpected. The molecule did seem to change shape but in a way that one carbon atom was bonded to six other carbon atoms. This result was never verified experimentally until now.

Moritz Malischewski and Konrad Seppelt, researchers at the Free University of Berlin, revived the experiment after more than 45 years. Creating the HMB molecule was a challenge as it remains stable only in an extremely strong acid. After creation, HMB was crystallized with other molecules and then, was subjected to X-rays to find out its crystal structure.

It was observed that one carbon atom jumped out of the hexagonal ring to form a 5 sided pyramid. It was bonded to the 5 atoms of the remaining ring and to 1 atom above it, according to ZME Science.

The ability of carbon to form six bonds is a testament to the fact that fundamental rules of science can change.  Our perception of the world is only limited to our observations and our observations are limited. So there will always be something to discover, something to invent and more so, something to marvel at in this world.