ISSN:
1573-1111
Keywords:
15-crown-5
;
18-crown-6
;
hydrogen bonding
;
uranyl perchlorate
;
low temperature crystal structure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The reaction of UO2(ClO4)·nH2O with 15-crown-5 and 18-crown-6 in acetonitrile yielded the title complexes. [UO2(OH2)5] [ClO4]2·3(15-crown-5)·CH3CN crystallizes in the triclinic space groupPT with (at−150°C)a=8.288(6),b=12.874(7),c=24.678(7) Å, α=82.62(4), β=76.06(5), γ=81.06(5)°, andD calc=1.67 g cm−3 forZ=2 formula units. Least-squares refinement using 6248 independent observed reflections [F o≥5σ(F o)] led toR=0.111. [UO2(OH2)5] [ClO4]2·2(18-crown-6)·2CH3CN·H2O is orthorhombicP212121 with (at−150 °C)a=12.280(2),b=17.311(7),c=22.056(3) Å,D calc=1.68 g cm−3,Z=4, andR=0.032 (3777 observed reflections). In each complex the crown ether molecules are hydrogen bonded to the water molecules of the pentagonal bipyramidal [UO2(OH2)5]2+ ions, each crown ether having exclusive use of two hydrogen atoms from one water molecule and one hydrogen from another water molecule. In the 15-crown-5 complex the remaining hydrogen bonding interaction is between one of the water molecules and one of the perchlorate anions. The solvent molecule has a close contact between the methyl group and a perchlorate anion suggesting a weak interaction. There are a total of three U-OH...OClO3 hydrogen bonds to the two perchlorate anions in [UO2(OH2)5] [ClO4]2·(18-crown-6)·2CH3CN ·H2O. The remaining coordinated water hydrogen bond is to the uncoordinated 2H2O molecule, which in turn is hydrogen bonded to a perchlorate oxygen atom and an acetonitrile nitrogen atom. One solvent methyl group interacts with an anion, the other with one of the 18-crown-6 molecules. Unlike the 15-crown-5 structure, the hydrogen bonding in this complex results in a polymeric network with formula units joined by hydrogen bonds from one of the solvent molecules and the uncoordinated water molecule.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00663006
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