N,N-Diethyl-2-hy-droxy-ethanaminium 5-(2,4-di-nitro-phen-yl)barbiturate sesquihydrate.

In the title hydrated mol-ecular salt, C6H16NO(+)·C10H5N4O7 (-)·1.5H2O [systematic name: N,N-diethyl-2-hy-droxy-ethan-am-in-ium 5-(2,4-di-nitro-phen-yl)-2,6-di-oxo-1,2,3,6-tetra-hydro-pyrim-idin-4-olate sesquihydrate], the dihedral angle between the six-membered rings in the anion is 37.66 (11)°. The nitro groups ortho and para to the ring junction are rotated from their attached ring by 40.8 (3) and 23.5 (3)°, respectively. The ethanol group is disordered over two of the 'arms' of the cation in a statistical ratio. In the crystal, [010] chains of anions occur, linked by N-H⋯O and O-H⋯O hydrogen bonds, which generate R 2 (2)(8) loops. Further N-H⋯O and O-H⋯O hydrogen bonds link the components into a three-dimensional network. One of the water O atoms lies near an inversion centre and is 50% occupied.


N,N-Diethyl-2-hydroxyethanaminium 5-(2,4-dinitrophenyl)barbiturate sesquihydrate Govindan Mangaiyarkarasi and Doraisamyraja Kalaivani Comment
Good crystallinity of the title barbiturate (pyrimidine derivative) and the biological effects of the related barbiturates (Kalaivani et al.,2008;Kalaivani & Buvaneswari,2010) necessitate us to subject the molecular salt of the present investigation for single-crystal X-ray analysis. The crystal structures of two different barbiturates with N,N-diethyl-2-hydroxyethanaminium cation have been reported by us recently (Buvaneswari & Kalaivani,2011;Babykala & Kalaivani,2012). No disorder has been observed in their cation moieties. The X-ray results of the molecular salt of present interest imply that the asymmetric unit consists of N,N-Diethyl-2-hydroxyethanaminium cation, 5-(2,4-dinitrophenyl)barbiturate anion and 1.5 molecules of water (Scheme). Fig.1 is the ORTEP diagram of the title molecule with 30% probability displacement ellipsoids. Disorder has been noticed in the ethanol group of diethylethanolammonium cation at two positions with equal probability (50% occupancy). The crystal structure features a number of N-H···O and O-H···O hydrogen bonds (Table.1) and these hydrogen bond interactions extend three dimensionally (Fig.2). O11 of water molecule is also disordered with its symmetry related position (sym:-x + 1,-y,-z + 2).The hydrogen atoms of O11 could not be located.In the anion, the dinitrophenyl ring and the barbiturate ring are not planar and the dihedral angle between them is 37.65 (0.09)°.The nitro groups attached to C3 and C1 atoms of phenyl ring make dihedral angles,23.51(0.15°) and 39.75(0.11°) respectively with the phenylplane. The inversion related barbiturate residues are linked through R 2 2 (8) motifs.
Experimental 1-Chloro-2,4-dinitrobenzene(2.02 g, 0.01 mol) was dissolved in 20 ml of ethanol and mixed with barbituric acid(1.2 g, 0.01 mol) dissolved in 30 ml of ethanol. To this mixture diethylethanolamine (5.85 g, 0.05 mol) was added,the red coloured solution obtained was shaken well for 3 h and kept as such at 25° C. Dark shiny maroon red crystals were deposited from the solution after 4 weeks. The crystals were washed with 5 ml of ethanol followed by 30 ml of ether, powdered well and was further washed with 40 ml of dry ether to remove unreacted reactants.The pure crystals thus obtained were recrystallized from hot ethanol(yield:85%; m.pt; 511 K). Red blocks were obtained by slow evaporation of an ethanol solution at room temperature.

Refinement
The initial refinement of the structure showed abnormal displacement ellipsoids for two chains of diethylethanolammonium ion, soon it could be identified as disorder arising from the ethanol and ethyl group exchanging positions.
The disordered components are suitably positioned and the occupancies refined, keeping the sum of occupancies as 1. As the occupancies convulsed to 50%, their values were fixed as 0.5 towards the last cycles of refinement. software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figure 1
The ORTEP diagram of the title compound with 30% probability displacement ellipsoids. Packing view of title compound.   (12) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (