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Ab initio structure determination of 5-anilinomethylene-2,2-dimethyl-1,3-dioxane-4,6-dione from laboratory powder data – a combined use of X-ray, molecular and solid-state DFT study

2007; Wiley; Volume: 63; Issue: 3 Linguagem: Inglês

10.1107/s0108768107006568

1600-5740

Ľubomír Smrčok, Vladimı́r Jorı́k, Eva Scholtzová, Viktor Milata,

Polymer Synthesis and Characterization

The crystal structure of the title compound was solved from laboratory powder diffraction data in the triclinic group P\bar 1 by simulated annealing using the program DASH. Since Rietveld refinements yielded inaccurate geometries the structure was finally refined by geometry optimization using energy minimization in the solid state with the DFT/plane-waves approach. The molecule is essentially planar and its Meldrum's acid moiety (2,2-dimethyl-1,3-dioxane-4,6-dione) has a flattened boat conformation. The bond orders in the molecule estimated using a natural bond-orbitals formalism correlate with the optimized bond lengths. The structure in the solid state is based on dimer units in which the molecules are held by N-H...O and C-H...O hydrogen bonds in addition to electrostatic interactions. These units interact through weak C-H...O hydrogen bonds. It is suggested that structure refinement by energy minimization at the DFT level of theory may in many cases successfully replace Rietveld refinement.