Crystal and molecular structure of benzotriazol-2-ylacetic acid: comparison between benzotriazol-1- and -2-yl systems

Abstract

Crystals of benzotriazol-2-ylacetic acid are monoclinic, space group P2₁/c with unit-cell parameters: a= 9.94(2), b= 8.48(2), c= 10.63(2)Å, β= 112.6(1)°, Z= 4. The structure was solved by direct methods and refined to R 0.044 for 727 observed reflections by block-diagonal least-squares. The molecules are linked in infinite chains parallel to b by a strong hydrogen bond, 2.70 Å in length. The planar 2-benzotriazole ring displays large π-electron delocalization and is compared with that in crystalline benzotriazol-1-ylacetic acid. Both systems are analysed in terms of valence-bond structures and their spectroscopic and chemical properties are correlated.