Three‐dimensional models of complex molecules, electron density contours, and text may be generated graphically and in stereo on a color television monitor by a 4096 word mini‐computer and prototype display system assembled from commercially available components. Interactive features include translation and rotation of the asymmetric unit for packing studies, rotation of the stereo image, and molecular geometry calculations.
C23H29NO 6 1637 the three planar segments in the molecule result in a rather loosely packed structure consistent with the ease of sublimation of the solid material.We wish to thank Dr Richard A. Kretchmer Least-squares refinement (nonhydrogen atoms anisotropic, H atoms isotropic) led to a final unweighted R value (on F; 1392 observed reflections) of 0.038. The carboxamide group is rotated by 34 ° from the plane of the pyridine ring and oriented such that the carbonyl O atom is directed toward the 4 position of the pyridine ring. The hybridization of the amide N is close to sp2; the chiral C atom, C(7), is 0.20A out of the plane of the carboxamide group. The phenyl group extends toward the B side of the molecule and the methyl group towards the A side. The conformation of the molecule is discussed in relation to studies of stereospecific reduction by models for the reduced pyridine nucleotide, NADH. It is found that the structure leads to predictions of asymmetric induction which are opposite to those experimentally observed.
Structure of (S)-N-(~-
The structure of spiro [5,5]undeca-l,4,7,10-tetraene-3,9-dione, C~IHsO2, has been determined from three-dimensional X-ray counter data. The crystals have the space group P]" with a= 9.080 (4), b= 13.608 (2), c=7.493 (3)/~, a=91"11 (2), fl=96-91 (4), y= 100.50 (2) ° and four molecules per unit cell. The observed and calculated densities are 1.26 (1) and 1.272 g cm -a respectively. 3180 independent reflections were collected by the 0=20 scan method. The structure was solved independently by two methods. In one method a three-dimensional color television display system was used to search for the most likely packing arrangements in the unit cell. The other method involved an application of Boolean programming. Both methods arrived at the same model, which was refined by least-squares techniques to a conventional R index of 0"048 for the 1485 reflections having I>_ 3at. The two independent molecules in the asymmetric unit are virtually identical and consist of two cyclodienone rings joined by a common spiro C atom. The average C-C bond length for bonds involving the spiro C atom is 1"50 (1)/~. The average bond angle around this atom is 109"4 ° .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.