title: 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.
abstract: 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.
authors.affiliation: Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 36 Bratislava, Slovakia. uachsmrk@savba.sk
authors.forename: Lubomír
authors.initials: L
authors.lastname: Smrcok
authors.forename: Vladimír
authors.initials: V
authors.lastname: Jorík
authors.forename: Eva
authors.initials: E
authors.lastname: Scholtzová
authors.forename: Viktor
authors.initials: V
authors.lastname: Milata