The crystal structures of {LnCu₅}³⁺ (Ln = Gd, Dy and Ho) 15-metallacrown-5 complexes and a reevaluation of the isotypic Eu^III analogue.

ABSTRACT: Three new isotypic heteropolynuclear complexes, namely penta-aqua-carbonato-penta-kis-(glycinehydroxamato)nitrato-penta-copper(II)lanthanide(III) x-hydrate, [LnCu₅(GlyHA)₅(CO₃)(NO₃)(H₂O)₅]·xH₂O (GlyHA^2- is glycine-hydrox-amate, N-hy-droxy-glycinamidate or amino-aceto-hydroxamate, C₂H₄N₂O₂ ^2-), with lanthanide(III) (Ln ^III) = gadolinium (Gd, 1, x = 3.5), dysprosium (Dy, 2, x = 3.28) and holmium (Ho, 3, x = 3.445), within a 15-metallacrown-5 class were obtained on reaction of lanthanide(III) nitrate, copper(II) acetate and sodium glycinehydroxamate. Complexes 1-3 contain five copper(II) ions and five bridging GlyHA^2- anions, forming a [CuGlyHA]₅ metallamacrocyclic core. The Ln ^III ions are coordinated to the metallamacrocycle through five O-donor hydroxamates. The electroneutrality of complexes 1-3 is achieved by a bidentate carbonate anion coordinated to the Ln ^III ion and a monodentate nitrate anion coordinated apically to one of the copper(II) ions of the metallamacrocycle. The lattice parameters of complexes 1-3 are similar to those previously reported for an Eu^III-Cu^II 15-metallacrown-5 complex with glycine-hydroxamate of proposed composition [EuCu₅(GlyHA)₅(OH)(NO₃)₂(H₂O)₄]·3.5H₂O [Stemmler et al. (1999 ?). Inorg. Chem. 38, 2807-2817]. High-quality X-ray data obtained for 1-3 have allowed a re-evaluation of the X-ray data solution proposed earlier for the EuCu₅ complex and suggest that the formula is actually [EuCu₅(GlyHA)₅(CO₃)(NO₃)(H₂O)₅]·3.5H₂O.

SUBMITTER: Pavlishchuk A 

PROVIDER: S-EPMC6690475 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature