C5H6N

C5H6N is a molecular formula representing several possible chemical species that share five carbon atoms, six hydrogen atoms, and one nitrogen atom. As a formula, it does not specify a single compound but a set of potential isomers, ions, or radicals. The nominal molecular weight of this composition is about 80.11 g/mol.

A key structural point is the degree of unsaturation. For a neutral, closed-shell molecule with this formula, the degree of unsaturation would be (2×5 + 2 + 1 − 6) / 2 = 3.5, a non-integer value. Since degree of unsaturation for a real, neutral molecule must be an integer, any isolated, non-radical species with the exact formula C5H6N would be impossible. In practice, therefore, entities labeled by C5H6N are typically ions or radicals or are considered as theoretical compositions in gas-phase or mass-spectrometric contexts.

In analytical contexts, C5H6N often appears as a proposed composition from high-resolution mass spectrometry. Distinguishing among possible structures—such as ionized or radical forms on a five-carbon framework, or small heterocycles with charge or unpaired electrons—requires additional data, including tandem mass spectrometry, isotope patterns, or spectroscopic information. Without such contextual data, the formula remains ambiguous and does not uniquely identify a single neutral compound.

See also: chemical formula, isomer, mass spectrometry, heterocycles, radical species.