HYDROGEN-BONDING INTERACTIONS IN THIOSEMICARBAZONES OF CARBOXYLIC-ACIDS - STRUCTURE OF 2-KETOBUTYRIC ACID THIOSEMICARBAZONE HEMIHYDRATE

G. ALZUET, S. F E R R E R , J. BORR/i,S A N D X. SOLANS A comparison of the crystal structure of Acm reported by Mathew & Palenik (1974) with that of MAcm, shows the following remarkable facts: (1) The N(3)--N(4) distance [1.374(3)A in MAcm, 1.372 (3) A in Acm] does not change despite the presence of a methyl group bonded to N(4) in MAcm. (2) The S(6)--N(8) bond len~gth is significantly shorter in MAcm [1-575(2) A] than in Acm [1 594 (3)/k]. (3) The C(2)--N(3)--N(4), N(3)--N(4)--C(5) and C(5)--N(11)--C(12) angles are modified in MAcm compared to Acm probably due to differences in the C(5)--N(4) and C(5)--N(11) bonds. (4) The hydrogen-bond system is clearly different in both structures, as could be expected since, on the one hand, there is one less H atom available and on the other, the methyl substituent on N(4) prevents the formation of hydrogen bonds by the N(3) and N(4) ring atoms. Thus, only one significant hydrogen bond is observed from MAcm in contrast to the three (involving the N-thiadiazole atoms as well) exhibited by Acm. We greatly appreciate C I C Y T ( F A R 88-502). financial support from References ALLEN, F. H., KENNARD, O., WATSON, D. G., BRAMMER, L., ORPEN, A. G. & TAYLOR, R. (1987). J. Chem. Soc. Perkin Trans 2, pp. SI-Sl9. ALZUET, G., FERRER, S. & BORR~,S, J. (1991). J. Inorg. Biochem. CHATTERJEE, C., DATTAGUPTA, J. K. & SAHA, N. N. (1981). Acta Cryst. B37, 1835-1838. CRUICKSHANK, D. W. J. (1961). J. Chem. Soc. pp. 5486-5504. JOHNSON, C. K. (1965). ORTEP. Report ORNL-3794. Oak Ridge National Laboratory, Tennessee, USA. MATHEW, M. & PALENIK, G. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 532-536. SHELDRICK, G. M. (1976). SHELX76. Program for crystal struc- ture determination. Univ. of Cambridge, England. SHELDRICK, G. M. (1990). Acta Cryst. A46, 467-473. YOUNG, R. W., WOOD, K. H., EICHLER, J. A., VAUGHAN, J. R. & ANDERSON, G. W. (1956). J. Am. Chem. Soc. 78, 4649-4654. Acta Cryst. (1991). C47, 2379-2381 Hydrogen-Bonding Interactions in Thiosemicarbazones of Carboxylic Acids: Structure of 2-Ketobutyric Acid Thiosemicarbazone Hemihydrate BY PRAMILA SONAWANE, RAJEEV CHIKATE, AVINASH KUMBHAR AND SUBHASH PADHYE Department of Chemistry, University of Poona, Pune 411 007, India AND ROBERT J. DOEDENS Department of Chemistry, University of California, Irvine, California 92717, USA (Received 3 December 1990; accepted 3 May 1991) Abstract. 2-Thiosemicarbazonobutanoic acid hemi- hydrate, CsH9N302S.0 5H20, Mr = 184.22, triclinic, P1, a = 8.163 (2), b = 8.868 (2), c = 12.438 (2) A, a = 72 99 (2), /3 = 79 47 (2), y = 84 06 (2) °, V= 845 3 (3) A 3, Z = 4, Dx = 1 447 Mg m -3, A(Mo Kce) = 0.71073 A, /.1. = 0.332 mm-1, F(000) = 392, T = 296 K, R = 0-038 for 3830 independent reflections with I > 3~r(/). Three hydrogen bonds link the two crystallographically independent molecules in a pair- wise fashion. The two molecules both have E con- figurations about each C - - N and N - - N bond, but differ by nearly 180 ° in the orientation of the - - C O O H group. Introduction. The structure of the title compound was determined in order to provide a point of com- parison with a series of complexes of trivalent transi- tion metal ions in which it is present as a ligand in its singly and doubly deprotonated forms. One such metal complex of a closely related ligand has already been reported (Timken, Wilson & Hendrickson, Experimental. The compound was prepared as described by Sah & Daniels (1950). Large rhombic- shaped plates were grown by slow evaporation of a saturated solution in boiling water. Data were col- lected on a Nicolet/Siemens R3m/V diffractometer from a fragment of dimensions 0 . 6 0 x 0 . 5 0 x 0.33 mm that had been cut from a larger crystal. Unit-cell parameters were obtained from the setting angles of 32 reflections with 30--- 20___ 40 ° . 0/20 scans. Data collected for 4 __ 20 ___ 60 ° with 0 _< h - < l l , - 1 2 - < k - - - 1 2 , - 1 6 - < l - - - 1 7 . No absorption © 1991 International Union of Crystallography

A comparison of the crystal structure of Acm reported by Mathew & Palenik (1974) with that of MAcm, shows the following remarkable facts: (1) The N(3)--N(4) distance [1.374(3)A in MAcm, 1.372 (3) A in Acm] does not change despite the presence of a methyl group bonded to N(4) in MAcm.
(4) The hydrogen-bond system is clearly different in both structures, as could be expected since, on the one hand, there is one less H atom available and on the other, the methyl substituent on N(4) prevents the formation of hydrogen bonds by the N(3) and N(4) ring atoms. Thus, only one significant hydrogen bond is observed from MAcm in contrast to the three (involving the N-thiadiazole atoms as well) exhibited by Acm.
Introduction. The structure of the title compound was determined in order to provide a point of comparison with a series of complexes of trivalent transi-0108-2701/91/112379-03503.00 tion metal ions in which it is present as a ligand in its singly and doubly deprotonated forms. One such metal complex of a closely related ligand has already been reported (Timken, Wilson & Hendrickson, 1985).

Atomic coordinates and equivalent isotropic thermal parameters (A 2)
U~q is the mean of the eigenvalues of the U tensor.

Table 2. Interatomic distances (A) and angles (°)
c (1) Symmetry codes: (i) 1 -x, 1 -y, z; (ii) 1 + x, y, z; (iii) 1 -x, I -y, 1 -z; (iv) x,y-l,z;(v)x,l+y,z-l;(vi)2-x, 1-y,z. * For each potential hydrogen-bond donor, the shortest contact to a potential acceptor is tabulated, subject to the constraint that the A--H...B angle is _> 140 °. Distances are not normalized. The number designating an H atom corresponds to that of the atom to which it is bound. The letter n or m denotes a hydrogen bound to nitrogen; other H atoms are bound to oxygen. the conformations of the two molecules. Additional hydrogen bonds connect this pair of molecules to the water of hydration and to other molecules. Details of the potential hydrogen-bonding interactions are included in Table 2. A number of these interactions are shown in Fig. 2, which depicts the unit-cell contents.
A search of the Cambridge Structural Database (Allen et al., 1979) reveals numerous thiosemicarbazones, but none that are derivatives of simple monocarboxylic acids. Pyruvic acid thiosemicarbazone also crystallizes as a hemihydrate (Timken, Wilson & Hendrickson, 1985) and may well have a similar crystal structure.