Conformational analysis and X-ray structure of 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid

The results of a X-ray structure determination and of a quantum-chemical Conformational analysis on the title compound are reported. The crystals belong to the triclinic system, space groupP¯1 (after structure determination), with two molecules in the unit cell, whose parameters are:a=11.966(2),b=8.118(2),c=7.693(2)A,α=97.03(2),β=92.98(2), γ=106.15(2)°: observed density (by flotation) 1.49, calculated 1.503 g cm−3. The structure was solved from 1815 diffractometer-measured intensities, withI≥2.5σ(I) and refined by full-matrix least-squares to a final conventional indexR=0.035 (R w =0.043). The most relevant feature of the molecular structure is the orientation of the dichlorophenyl ring with respect to the planar indazole group, the dihedral angle being 83.1(1)°. A very close conformation corresponds to one of the minima calculated by the semiempirical AMI method.