Structure of 1H-indazole-3-carboxylic acid

Abstract

Experimental. A prismatic white crystal of dimensions 0.70 × 0.48 × 0.40 mm was lodged in a Lindemann glass capillary and centred on a four-circle Philips PWll00 diffractometer with graphitemonochromated Mo K~ radiation. The orientation matrix and preliminary unit-cell dimensions were determined from 25 reflections found by mounting the crystal at random, varying each of the orientation angles X and ~ over a range of 120 °, with 7 _< 0 < 9 °. For the determination of precise lattice parameters, 25 strong reflections with 9 ___ 0---14 ° were considered. Integrated intensities for hkl reflections in the interval h = _+ 12, k = 0---,17, l = 0~11, 0 = 2-25 ° , were measured using 0/20 scans, and two standard reflections, 7462 and 341, were measured every 180 min. There were no significant fluctuations of intensities other than those expected from Poisson statistics. In total, 2878 reflections were measured, of which 2595 were unique with 2105 being observed [I _ 2.50-(/)]. The intensity data were collected at room temperature and corrected for Lorenz-polarization effects but not for absorption.0108-2701/93/040779-03506.00The structure was solved by using direct methods (SHELXS86; Sheldrick, 1985) and refined with fullmatrix least squares; anisotropic thermal parameters were assigned to all non-H atoms. H atoms were located by difference Fourier synthesis and refined isotropically.

A Solid-State NMR, X-ray Diffraction, and ab Initio Computational Study of Hydrogen-Bond Structure and Dynamics of Pyrazole-4-Carboxylic Acid Chains

“…On the other hand, the carboxylic acid groups can be expected to act as an acid and the pyrazole groups as a base. Evidence for such a situation was obtained recently by X-ray diffraction of 2-aminopyrazole-carboxylic acid, which forms a zwitterionic ribbon in the solid state with two O···H−N hydrogen bonds, as depicted in Figure g. On the other hand, the acid−base interaction is much weaker in 1 H -indazole-3-carboxylic acid, which forms a tetramer supercycle with four pyrazole-carboxylic acid links .…”

Trifluoro‐3‐hydroxy‐1H‐indazolecarboxylic Acids and Esters from Perfluorinated Benzenedicarboxylic Acids

“…The two ethyl esters 6 and 9 and the carboxylic acid 7 show the same trend: a slight variation in N‐1 and a remarkable increase in N‐2. In addition to their existing as their 3‐hydroxy tautomers, the small chemical shift differences between these two compound frameworks and their methyl analogues 5 and 8 suggest that these four derivatives should be arranged in similar modes in their crystalline structures, probably involving N–H ··· N hydrogen bonds, although involvement of the carbonyl oxygen in the alkoxycarbonyl group in hydrogen bonding cannot be ruled out 25,26. With regard to compound 3 , the values reported in Table 4 are significantly different; probably an IMHB between ethoxycarbonyl and OH groups prevents the formation of dimeric structures such as those shown in Figures 3 and 6.…”

5-Phenylindazole

“…Two types of hydrogen-bonding network are possible for NH-indazoles, catemers and trimers. In the first group, indazole molecules (Escande & Lapasset, 1974) are linked by N--H...N hydrogen bonds while in 1H-indazole-3-carboxylic acid (Benetollo & Del Pra, 1993), the molecules are bonded through N--H...O bonds reinforced by O-H.. • N interactions. Trimers are formed via N--H...N bonds in 3-phenyl-5-methyl-lH-indazole (Dvorkin et al, 1989) and via N--H...O/N three-centre bonds in 3-methoxycarbonyl-lH-indazole (Glaser, Mummert, Horan & Barnes, 1993).…”