Crystal and molecular structure of pyroglutamic acid (5-oxoproline)

Abstract

The crystal structure of the title compound has been determined by the symbolic addition method from 934 observed three-dimensional photographic data. Crystals are monoclinic with a= 8·14, b= 8·86, c= 9·32 Å(all ±0·02 Å), and β= 116·5°(2),Z= 4, space group P2₁/c. The structure was refined by full-matrix least-squares method to R 0·091. The structure is stabilised by N–H ⋯ O and O–H ⋯ O type hydrogen bonds. The dimensions of the amide group, which is significantly non-planar, are compared with those found in other peptides.