Crystal structure of a Tb III -Cu II glycine-hydroxamate 15-metallacrown-5 sulfate complex.

The core of the title complex, bis-[hexa-aqua-hemi-aqua-penta-kis-(μ 3 -glycine-hydroxamato)sulfato-penta-copper(II)terbium(III)] sulfate hexa-hydrate, [TbCu 5 (SO 4 )(GlyHA) 5 (H 2 O) 6.5 ] 2 (SO 4 )·6H 2 O ( 1 ), which belongs to the 15-metalla-crown-5 family, consists of five glycine-hydroxamate dianions (GlyHA 2- ; C 2 H 4 N 2 O 2 ) and five copper(II) ions linked together forming a metallamacrocyclic moiety. The terbium(III) ion is connected to the centre of the metallamacrocycle through five hydroxamate oxygen atoms. The coordination environment of the Tb 3+ ion is completed to an octa-coordination level by oxygen atoms of a bidentate sulfate and an apically coordinated water mol-ecule, while the copper(II) atoms are square-planar, penta- or hexa-coordinate due to the apical coordination of water mol-ecules. Continuous shape calculations indicate that the coordination polyhedron of the Tb 3+ ion in 1 is best described as square anti-prismatic. The positive charge of each pair of [TbCu 5 (GlyHA) 5 (H 2 O) 6.5 (SO 4 )] 2 2+ fragments is compensated by a non-coordinated sulfate anion, which is located on an inversion center with 1:1 disordered oxygen atoms. Complex 1 is isomorphous with the previously reported compounds [ Ln Cu 5 (GlyHA) 5 (SO 4 )(H 2 O) 6.5 ] 2 (SO 4 ), where Ln III = Pr, Nd, Sm, Eu, Gd, Dy and Ho.