The crystal structures of {Cu} ( = Gd, Dy and Ho) 15-metallacrown-5 complexes and a reevaluation of the isotypic Eu analogue.

Three new isotypic heteropolynuclear complexes, namely penta-aqua-carbonato-penta-kis-(glycinehydroxamato)nitrato-penta-copper(II)lanthanide(III) -hydrate, [Cu(GlyHA)(CO)(NO)(HO)]·HO (GlyHA is glycine-hydrox-amate, -hy-droxy-glycinamidate or amino-aceto-hydroxamate, CHNO ), with lanthanide(III) ( ) = gadolinium (Gd, , = 3.5), dysprosium (Dy, , = 3.28) and holmium (Ho, , = 3.445), within a 15-metallacrown-5 class were obtained on reaction of lanthanide(III) nitrate, copper(II) acetate and sodium glycinehydroxamate. Complexes - contain five copper(II) ions and five bridging GlyHA anions, forming a [CuGlyHA] metallamacrocyclic core. The ions are coordinated to the metallamacrocycle through five O-donor hydroxamates. The electroneutrality of complexes - is achieved by a bidentate carbonate anion coordinated to the ion and a monodentate nitrate anion coordinated apically to one of the copper(II) ions of the metallamacrocycle. The lattice parameters of complexes - are similar to those previously reported for an Eu-Cu 15-metallacrown-5 complex with glycine-hydroxamate of proposed composition [EuCu(GlyHA)(OH)(NO)(HO)]·3.5HO [Stemmler (1999 ▸). , 2807-2817]. High-quality X-ray data obtained for - have allowed a re-evaluation of the X-ray data solution proposed earlier for the EuCu complex and suggest that the formula is actually [EuCu(GlyHA)(CO)(NO)(HO)]·3.5HO.