The crystal and molecular structure of dichlorobis(hexamethylphosphoramide)dioxouranium(VI): UO₂Cl₂.2(HMPA)

Abstract

The title compound is tetragonal with a = 10.430 (5), c = 23.82 (1) A, Z = 4, space group P4~2~2. The structure was determined by Patterson and Fourier methods and refined by full-matrix least squares to a final R of 0.037 for 924 observed reflexions. The U atom is octahedraily coordinated with the HMPA iigands in the trans position.

Synthesis and crystal structure of [UO2(BH4)2(hmpa)2], a novel uranyl complex and the first metal oxoborohydride

“…This mode of attachment of the tetrahedral BH 4 ligand should be preferred over the tridentate ligation pattern in which the coordinating hydrogen atoms would be displaced from the equatorial plane [14]. In agreement with the variation in the radii of the U 4+ and U 6+ ions [15], the U Á Á Á B(1) and U Á Á Á B(2) distances of 2.713(9) and 2.833 (12) Å are smaller than those of bidentate BH 4 ligands in uranium(IV) complexes, which vary from 2.84 (5) (18-crown-6)] [17]; these U Á Á Á B distances are larger than those of tridentate borohydrides of uranium(IV) which average 2.6(1) Å from the Cambridge Structural Database [18].…”

“…1 together with selected distances and angles. The crystals are isomorphous with those of [UO 2 X 2 (hmpa) 2 ] (X = Cl [12], Br [11c], I [11c], NO 3 [13]); the line passing through the U and B atoms is a C 2 axis of symmetry. The U@O(1) and U-O(2) distances of 1.760(4) and 2.296(4) Å are identical to those measured in the halide and nitrate congeners.…”

Convenient syntheses of uranyl(VI) cis-dihalide complexes as anhydrous starting materials

“…A thermal ellipsoid drawing of 2a is shown in Fig. 1 along with selected bond distances and bond angles; a thermal ellipsoid drawing for the bromide derivative 3a is shown in Figure S1 The interatomic U@O, U-O (amide) [19,20] and U-N (pyridyl) [21] bond distances are all within the normal range for uranyl complexes, as are the respective U-Cl [22][23][24] and U-Br [2,5,25] These are the widest angles between adjacent equatorial ligands in these complexes; for comparison, reflecting the steric congestion that these large atoms place upon the remainder of the equatorial region, the most acute angle is that between N(1)-U(1)-O(2), at 61.48(7) in 2a and 61.04(17)°i n 3a. Possible steric strain induced by the crowded equatorial coordination sphere is evident in the conformation of the tridentate ligand, where the pyridyl ring is tilted approximately 30°with respect to the equatorial plane in both structures.…”

Crystal structure of trichlorooxo-17-bis[(diphenylphosphoryl)methyl]- 4(24),6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20- tetrapentylresorcin[4]areneuranium(V) -dichlorodioxo-17- bis[(diphenylphosphoryl)methyl]-4(24),6(10),12(16),18(22)- tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]areneuranium(VI) - hexane (1:3:3), UCl3O(C78H86O10P2) · 3UCl2O2(C78H86O10P2) · 3C6H14

“…plex) lie in the range found in other uranyl-(phosphine oxide) complexes [3][4][5][6][7]. The endo oriented U-Cl bonds length are somewhat shorter than the exo ones.…”