Synthesis and Structural Characterisation of Copper(II) 15‐Metallacrown‐5 Complexes with Pb^II, Hg^II, Ag^I, Na^I and Y^III Central Metal Ions

Abstract

The new copper (II)

Synthesis and Molecular Structures of CuII 15‐Metallacrown‐5 Complexes with Encapsulated CaII, PrIII and NdIII Ions

“…As in the case of Ln III containing 15‐MC‐5 single crystals suitable for X‐ray analysis could not be obtained, instead an alternative synthetic method based on redissolution of the crude complexes in pyridine, which acts both as a solvent and an additional ligand was used. This method was previously employed to obtain single crystals of Pb II ‐Cu II and Hg II ‐Cu II 15‐MC‐5 17. As a result, in currently obtained Pr III and Nd III ‐Cu II 15‐MC‐5 complexes, all the axial positions of Cu II and one axial position of Ln III ions appear to be occupied by pyridine molecules.…”

“…On the other hand, α‐aminohydroxamates, able to form only five‐ membered chelate rings, tend to form pentagonal 15‐MC‐5 structures, where the metallamacrocyclic circuit can be formed with metals as Cu II , Ni II , Zn II , Mn III ,6,9–10 and a central cavity can encapsulate a metal ion with suitable radius (Scheme , right). Up to now heteropolynuclear 15‐MC‐5 complexes containing Ln III ,8–16 Y III , Pb II , Hg II , Ag I , Na I , Ca II , and UO 2 2+ as central cavity ions have been obtained 17–21…”

“…2‐Picolinehydroxamic acid (o‐picHA) is one of the most used hydroxamate ligands in the synthesis of MC complexes. Earlier its Cu II 15‐MC‐5 compounds with encapsulated Gd III and Eu III ions,8a UO 2 2+ ,19 and Pb II and Hg II ions17 have been obtained and structurally characterized. Ni II and Zn II 15‐MC‐5 complexes with Ln III ions in the central cavity have been also synthesized; some of them structurally characterized 18,20.…”

“…Ni II and Zn II 15‐MC‐5 complexes with Ln III ions in the central cavity have been also synthesized; some of them structurally characterized 18,20. Cu II 15‐MC‐5 complexes with Na I and Ca II in the center of the cavity17,21 have been also reported, however, single‐crystal X‐ray diffraction analysis has not been carried out. Also, heterometallic Cu II 15‐MC‐5 complexes based on o ‐picHA with Pr III and Nd III in the central cavity have not been reported in the literature until now.…”

Clarifying the Mechanism of Cation Exchange in Ca(II)[15-MCCu(II)Ligand-5] Complexes

“…[23][24][25]44,45 To establish the actual process, and to give an interpretation of the kinetic behavior of the Ca−Ln substitution reaction, we decided to study the possible mechanism of substitution of the core metal through mass spectrometric analyses of the products of the substitution reaction where two Ca II metallacrowns with very similar ligands are involved. This technique proved itself to be a very powerful approach to study both the speciation and the reactivity of self-assembled supramolecular complexes, 46 Mixed-ligands Ln III metallacrowns are, therefore, not obtained starting from preassembled Ca II MC species, but they are the main species when the metallacrowns are assembled from initial components (i.e., mixing Ca II , Cu II , Trpha and Pheha).…”