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- Title
Formation of co-racemic uranyl chromate constructed from chiral layers of different topology.
- Authors
Siidra, Oleg; Nazarchuk, Evgeny; Bocharov, Sergey; Depmeier, Wulf; Zadoya, Anastasiya
- Abstract
Four new inorganic uranyl chromates were obtained by evaporation and hydrothermal methods: [(CH3)2NH2]2[(UO2)2(CrO4)3(H2O)](H2O) (1), K(Rb0.6K0.4)[(UO2)2(CrO4)3(H2O)](H2O)3 (2) [(CH3)3CNH3]2[(UO2)2- (CrO4)3H2O] (3), [(CH3)2NH2]4[(UO2)2(CrO4)3H2O]2(H2O) (4). Their structures are based on two-dimensional chiral or achiral units with the composition [(UO2)2(CrO4)3(H2O)]2- and two types of topologies (A or/and B). The structural architecture of (4) is unique amongst all known uranyl-based structures, and unusual among hybrid organic/inorganic structures in general as it contains layers of identical composition, but of different topology. The unique structural configurations and non-centrosymmetry in (1) and (4) is governed by selective formation of hydrogen bonding rather than by the formation of hydrophobic and hydrophilic zones in the organic interlayer. It is shown that chiral architectures in uranyl systems may form from achiral building units as observed in (3) and (4). This is somewhat analogous to certain organic compounds, where achiral molecules are also able to form chiral layers. Within the concept of such an interpretation the structure of (3) can then be described as a racemate consisting of two A and A' chiral layers. In a similar approach the structure of (4) can be interpreted as being formed by four chiral layers. Layer pairs AA' and BB0 can then be considered as racemic pairs and the whole structure is a co-racemate built by a combination of two racemates. Two-stage formation can be suggested for (4).
- Subjects
URANYL compounds; CHIRALITY; HYDROGEN bonding
- Publication
Acta Crystallographica Section B: Structural Science, Crystal Engineering & Materials, 2017, Vol 73, Issue 1, p101
- ISSN
2052-5192
- Publication type
Article
- DOI
10.1107/S205252061601917X