2-Pyridone: monoclinic polymorph

The asymmetric unit in the title compound, C(5)H(5)NO, comprises two independent but virtually identical mol­ecules of 2-pyridone, and represents a monoclinic polymorph of the previously reported ortho­rhom­bic (P2(1)2(1)2(1)) form [Penfold (1953 ▶). Acta Cryst. 6, 591–600; Ohms et al. (1984 ▶). Z. Kristallogr. 169, 185–200; Yang & Craven (1998 ▶). Acta Cryst. B54, 912–920]. The independent mol­ecules are linked into supra­molecular dimers via eight-membered {⋯HNC(O)}(2) amide synthons in contrast to the helical supra­molecular chains, mediated by {⋯HNC(O)} links, found in the ortho­rhom­bic form.