Journal
JOURNAL OF MOLECULAR STRUCTURE
Volume 889, Issue 1-3, Pages 217-228Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.molstruc.2008.02.005
Keywords
s-Heptazine derivatives; Molecular modeling; Chemical shift anisotropy; X-ray powder diffraction; Hydrogen bonding
Categories
Funding
- Deutsche Forschungsgemeinschaft (DFG) [SE-1417/1-1, SE-1417/2-1]
Ask authors/readers for more resources
We present the structure solution for solvent-free cyameluric acid which has first been synthesized more than 150 years ago. By densely intertwining the complementary methods solid-state NMR spectroscopy, molecular modeling as well as direct-space methods for the analysis of the X-ray powder diffraction data we succeeded where conventional powder diffraction analysis alone failed. In a first step, the correct tautomer was identified by combining solid-state NMR and ab initio calculations. The quantum-chemically optimized molecule was further employed in direct-space methods for the crystal structure solution. After a subsequent Rietveld refinement the positions of the hydrogen atoms in the crystal were determined by comparing experimental and calculated NMR chemical shift parameters. In this context, the sensitivity of the anisotropy delta(aniso) and the asymmetry parameter eta of the carbonyl C-13 towards the hydrogen bonding environment proved to be very valuable. Cyameluric acid crystallizes in space group P2(1)2(1)2(1) (Z = 4, a = 6.4701(5) angstrom, b = 9.9340(6) angstrom, c = 12.0985(7) angstrom) with one complete molecule in the asymmetric unit. It consists of the symmetric trioxo tautomer which is arranged in a three-dimensional hydrogen bond network where all three NH groups interact with carbonyl groups. (C) 2008 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available