IUCr journals

Two scandium–biuret complexes: [Sc(C2H5N3O2)-(H2O)5]Cl3.H2O and [Sc(C2H5N3O2)4](NO3)3 

Acta Cryst. (2008). C64, m205–m208 [doi:10.1107/S010827010800824X]

[Structure]The molecular structure of [Sc(C3H5N2)4]3+.
Scandium(III) shows unusual flexibility in its coordination number in complexes, and six-, seven-, eight- and nine-coordinate species are known. When combined with biuret and water molecules, distinctive, near regular, pentagonal bipyramidal [Sc(H2O)5(C3H5N2)]3+ and square antiprismatic [Sc(C3H5N2)4]3+ geometries arise, suggesting that the counter-ion may play some role in defining the metal coordination preference.

W.T.A. Harrison