Nanoscale hemispheres in novel mixed-valent uranyl chromate(V,VI), (C3NH10)10[(UO2)13(Cr12(5+)O42)(Cr(6+)O4)6(H2O)6](H2O)6.
The structure of a novel mixed-valent chromium uranyl compound, (C(3)NH(10))(10)[(UO(2))(13)(Cr(12)(5+)O(42))(Cr(6+)O(4))(6)(H(2)O)(6)](H(2)O)(6) (1), obtained by the combination of a hydrothermal method and evaporation from aqueous solutions with isopropylammonium, contains uranyl chromate hemispheres with lateral dimensions of 18.9 × 18.5 Å(2) and a height of about 8 Å. The hemispheres are centered by a UO(8) hexagonal bipyramid surrounded by six dimers of Cr(5+)O(5) square pyramids, UO(7) pentagonal bipyramids, and Cr(6+)O(4) tetrahedra. The hemispheres are linked into two-dimensional layers so that two adjacent hemispheres are oriented in opposite directions relative to the plane of the layer. From a topological point of view, the hemispheres have the formula U(21)Cr(23) and can be considered as derivatives of nanospherical cluster U(26)Cr(36) composed of three-, four-, and five-membered rings.
Department of Crystallography, St. Petersburg State University, University emb. 7/9, St. Petersburg, 199034 Russia. siidra@mail.ru
Oleg I
OI
Siidra
Evgeny V
EV
Nazarchuk
Anatoly A
AA
Petrunin
Roman A
RA
Kayukov
Sergey V
SV
Krivovichev