Two polymorphs and the diethylammonium salt of the barbiturate eldoral.
Polymorph (Ia) of eldoral [5-ethyl-5-(piperidin-1-yl)barbituric acid or 5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione], C(11)H(17)N(3)O(3), displays a hydrogen-bonded layer structure parallel to (100). The piperidine N atom and the barbiturate carbonyl group in the 2-position are utilized in N-H···N and N-H···O=C hydrogen bonds, respectively. The structure of polymorph (Ib) contains pseudosymmetry elements. The two independent molecules of (Ib) are connected via N-H···O=C(4/6-position) and N-H···N(piperidine) hydrogen bonds to give a chain structure in the [100] direction. The hydrogen-bonded layers, parallel to (010), formed in the salt diethylammonium 5-ethyl-5-(piperidin-1-yl)barbiturate [or diethylammonium 5-ethyl-2,4,6-trioxo-5-(piperidin-1-yl)-1,3-diazinan-1-ide], C(4)H(12)N(+)·C(11)H(16)N(3)O(3)(-), (II), closely resemble the corresponding hydrogen-bonded structure in polymorph (Ia). Like many other 5,5-disubstituted derivatives of barbituric acid, polymorphs (Ia) and (Ib) contain the R(2)(2)(8) N-H···O=C hydrogen-bond motif. However, the overall hydrogen-bonded chain and layer structures of (Ia) and (Ib) are unique because of the involvement of the hydrogen-bond acceptor function in the piperidine group.
Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria. thomas.gelbrich@uibk.ac.at
Thomas
T
Gelbrich
Denise
D
Rossi
Ulrich J
UJ
Griesser
D001463:Barbiturates / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D010880:Piperidines / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012492:Salts; D014227:Triazines / Q000737:chemistry*; D014299:Trimipramine / Q000737:chemistry*
C571032:5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione; D001463:Barbiturates; D010880:Piperidines; D000644:Quaternary Ammonium Compounds; D012492:Salts; D014227:Triazines; D014299:Trimipramine