Crystallographic and conformational investigations of some organic compounds

Molecular and crystal structure of 4-(2-furylmethylene)-2-(4-methylphenyl)-5-oxazolone and N,N'-Bis-(3,5-dioxo-4-azatricyclo[5.2.1.02,6]dec-8-en-4-yl) oxalamide have been determined by single crystal X-ray diffraction study.The oxazolone compound which was crystallized in monoclinic crystal system and solved by direct methods with using a total of 950 reflections. Structure was refined by least-square and difference-Fourier methotds to a conventional R=0,048 for 204 parameters. The bond lenghts and angles of the oxazolone ring are comparable in the literature. The C atom between the furyl and oxazolone rings displays a distorted trigonal bonding geometry. The molecule is almost planar and adopts the Z configuration. Besides, this result proved by PM3 semi-empirical method and according as the selected torsion angle T(N1-C9-C10-C11) in the molecule, energy profile is calculated. The crystal structure stabilized C-H?O type intermolecular, pi-pi and C-O...pi weak interactions.The oxalamide compound which was crystallized in triclinic system is related to P-1 space group. The molecular structure was solved by direct methods with using a total of 3428 reflections. The structure was refined by least-square and difference-Fourier methotds to a conventional R=0.041 for 234 parameters. The half oxalamide molecule is in the asymmetric unit together with one dimethylformamide solvent molecule. The molecule has a inversion centre on the middle point of the molecule. The two C=O groups lie on opposite sides of the bond C10-C10i and the molecule adopts the trans conformation. The bicycloheptene ring adopts a boat conformation. The crystal structure stabilized by N-H?O and C-H?O type intermolecular interactions.