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Different molecular conformations co‐exist in each of three 2‐aryl‐ N ‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1 H ‐pyrazol‐4‐yl)acetamides: hydrogen bonding in zero, one and two dimensions
Author(s) -
Narayana Badiadka,
Yathirajan Hemmige S.,
Rathore Ravindranath S.,
Glidewell Christopher
Publication year - 2016
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229616012870
Subject(s) - hydrogen bond , acetamide , molecule , chemistry , isostructural , aryl , stereochemistry , crystallography , crystal structure , organic chemistry , alkyl
4‐Antipyrine [4‐amino‐1,5‐dimethyl‐2‐phenyl‐1 H ‐pyrazol‐3(2 H )‐one] and its derivatives exhibit a range of biological activities, including analgesic, antibacterial and anti‐inflammatory, and new examples are always of potential interest and value. 2‐(4‐Chlorophenyl)‐ N ‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1 H ‐pyrazol‐4‐yl)acetamide, C 19 H 18 ClN 3 O 2 , (I), crystallizes with Z ′ = 2 in the space group P , whereas its positional isomer 2‐(2‐chlorophenyl)‐ N ‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1 H ‐pyrazol‐4‐yl)acetamide, (II), crystallizes with Z ′ = 1 in the space group C 2/ c ; the molecules of (II) are disordered over two sets of atomic sites having occupancies of 0.6020 (18) and 0.3980 (18). The two independent molecules of (I) adopt different molecular conformations, as do the two disorder components in (II), where the 2‐chlorophenyl substituents adopt different orientations. The molecules of (I) are linked by a combination of N—H…O and C—H…O hydrogen bonds to form centrosymmetric four‐molecule aggregates, while those of (II) are linked by the same types of hydrogen bonds forming sheets. The related compound N ‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1 H ‐pyrazol‐4‐yl)‐2‐(3‐methoxyphenyl)acetamide, C 20 H 21 N 3 O 3 , (III), is isomorphous with (I) but not strictly isostructural; again the two independent molecules adopt different molecular conformations, and the molecules are linked by N—H…O and C—H…O hydrogen bonds to form ribbons. Comparisons are made with some related structures, indicating that a hydrogen‐bonded R 2 2 (10) ring is the common structural motif.