Bis(1,3-dimethyl-1,3-diazinan-2-one)dinitratodioxidouranium(VI)

The title compound, [U(NO3)2O2(C6H12N2O)2], exhibits a hexagonal–bipyramidal geometry around the UVI ion, which is situated on an inversion centre and coordinated by two oxide ligands in the axial positions, and four O atoms from two bidentate NO3 − and two O atoms from two 1,3-dimethyl-1,3-diazinan-2-one (DMPU) ligands in the equatorial plane. These ligands are located in trans positions. The –(CH2)3– moiety in the DMPU ligand is disordered over two positions in a 0.786 (11):0.214 (11) ratio.

The title compound, [U(NO 3 ) 2 O 2 (C 6 H 12 N 2 O) 2 ], exhibits a hexagonal-bipyramidal geometry around the U VI ion, which is situated on an inversion centre and coordinated by two oxide ligands in the axial positions, and four O atoms from two bidentate NO 3 À and two O atoms from two 1,3-dimethyl-1,3diazinan-2-one (DMPU) ligands in the equatorial plane. These ligands are located in trans positions. The -(CH 2 ) 3 -moiety in the DMPU ligand is disordered over two positions in a 0.786 (11):0.214 (11) ratio.
The two uranyl oxo atoms (O1) from the uranyl(VI) ion occupy the axial position of U1, and two carbonyl oxygen atoms (O2) from the two unidentate DMPU and four oxygen atoms (two O3 and two O4) from the two bidentate NO 3 are situated in the trans positions in the equatorial plane of U1 (Fig. 1). The selected parameters are listed in Table 1 (Varga, et al., 2003;Ikeda et al., 2004).
The differences in U-O bonds are considered to be due to those in donicity and size of L. In the dmpu ligand, C3 and C3B display disorder in a 0.786 (11) and 0.214 (11) occupancy ratio. To 1 ml of the UO 2 2+ solution was added 1 mmol of DMPU with vigorous stirring. Yellow precipitate was obtained. The resulting precipitate was filtered off, and washed with hexane. The precipitate was recrystallized from dichloromethane.

Refinement
All H atoms were positionated geometrically, with C-H 0.98 and 0.99 Å for methyl and methylene H atoms, and constrated to ride on their parent atoms, with U iso (H) = 1.2U eq (C). Fig. 1. Molecular view of I with 30% thermal ellipsoids [symmetry code: i) -x + 2, -y, -z + 2]. Hydrogen atoms are omitted for clarity.

Bis(1,3-dimethyl-1,3-diazinan-2-one)dinitratodioxidouranium(VI)
Crystal data [U(NO 3  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 > 2σ(F 2 ) is used only for calculating Rfactors(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. (