Cation–anion CH⋯O− interactions in the metal-free phenolate, tetra-n-butylammonium phenol-phenolate

Deprotonation of phenol by tetra-n-butylammonium hydroxide and subsequent removal of water by P2O5 results in quantitative formation of tetra-n-butylammonium phenol-phenolate. The compound crystallizes as an ion pair, with the solute phenol molecule intimately attached to the phenolate anion by an O–H⋯O− hydrogen bond (O⋯O 2.471(5) Å). A short contact between one α-C atom of the tetra-n-butylammonium cation and the phenolate O atom indicates that the ion pair interaction is strengthened by an additional C–H⋯O− hydrogen-bond, despite the attached phenol.