Acta Cryst. (2008). C64, m205-m208 [ doi:10.1107/S010827010800824X ]
Abstract: The scandium(III) cations in the structures of pentaaqua(biuret-![[kappa]](/logos/entities/kappa_rmgif.gif)
2O,O')scandium(III) trichloride monohydrate, [Sc(C2H5N3O2)(H2O)5]Cl3·H2O, (I), and tetrakis(biuret-2O,O')scandium(III) trinitrate, [Sc(C2H5N3O2)4](NO3)3, (II), are found to adopt very different coordinations with the same biuret ligand. The roles of hydrogen bonding and the counter-ion in the establishment of the structures are described. In (I), the Sc3+ cation adopts a fairly regular pentagonal bipyramidal coordination geometry arising from one O,O'-bidentate biuret molecule and five water molecules. A dense network of N-H
Cl, O-HO and O-HCl hydrogen bonds help to establish the packing, resulting in dimeric associations of two cations and two water molecules. In (II), the Sc3+ cation (site symmetry 2) adopts a slightly squashed square-antiprismatic geometry arising from four O,O'-bidentate biuret molecules. A network of N-HO hydrogen bonds help to establish the packing, which features [010] chains of cations. One of the nitrate ions is disordered about an inversion centre. Both structures form three-dimensional hydrogen-bond networks.
Formula: [Sc(C2H5N3O2)(H2O)5]Cl3·H2O and [Sc(C2H5N3O2)4](NO3)3
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