Keto–enol tautomerism, conformations and structure of N-(2-hydroxy-5-methylphenyl), 2-hydroxybenzaldehydeimine

Abstract

N-(2-hydroxy-5-methylphenyl), 2-hydroxybenzaldehydeimine (C 14H 13NO 2) has been studied by X-ray analysis and AM1 semi-empirical quantum mechanical method. It crystallizes in the monoclinic space group P2 1/c with a=7.433(1), b=9.185(3), c=186(4) Å, β=97.13(1)°, V=1164.3(5) Å 3, Z=4, D c=1.30 gcm −3 and μ(MoK α)=0.087 mm −1. The structure was solved by direct methods and refined to R=0.034 for 1407 reflections [ I>2σ( I)]. The title compound is photochromic and the molecule is not planar. Intramolecular hydrogen bonds occur between the pairs of atoms N(1) and O(1) [2.582(1) Å], and N(1) and O2) [2.655(1) Å], the H atom essentially being bonded to the N atom. Adjacent molecules are linked via an intermolecular O–H⋯O hydrogen bond [2.582(1) Å] between neighbouring molecules. Tautomeric properties and conformations of the title compound were investigated by semi-empirical quantum mechanical AM1 calculations and the results are compared with the X-ray results.