Adamantane

Adamantane is the saturated cage hydrocarbon ${\mathrm{C}}_{10}{\mathrm{H}}_{16}$. Its carbon framework is a compact three-dimensional network of fused chair-like six-membered rings, with the connectivity recorded by its tricyclic structural name.^[ref]

The rigid cage restricts conformational motion. Symmetry can make several carbon or hydrogen positions equivalent in a spectrum, while substitution breaks those equivalences. The molecule therefore provides a useful example of how three-dimensional connectivity and molecular symmetry influence chemical reactivity and spectroscopic counting.