Question

Why do geometric isomers exist?

Answer 1

Simply because they can exist.

Explanation:

Geometric isomers are isomers of the same connectivity yet different spatial geometry. Given the wealth of carbon chemistry, geometric isomerism can be observed for even simple organic molecules. Such isomerism can also be observed in inorganic chemistry, though this area is not so well-developed.

We can take a simple organic molecule, say `"2-butylene"`, `H_3C-CH=CH-CH_3`. The disposition of the methyl groups across the double bonds generates two geometric isomers (which are?), and these isomers have different chemical and physical properties even though their `C-C` connectivity is the same. As molecules get bigger, the opportunity for geometric isomerism becomes greater. Synthetic chemists are generally good at selecting the right conditions to select the right isomer, but a lot of work is involved.