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 (Eur. J. Inorg. Chem. 19/2007)

Abstract

The cover picture shows the 5‐metallacrown‐5 complex, which is obtained by the self‐assembly of five copper(II) ions, five 2‐picolinehydroximate ligands (picha) and the central mercury(II) ion. The (15‐metallacrown‐5)HgII and ‐PbII complexes have been obtained in the crystalline form as pyridine adducts [HgCu5(picha)5(py)7](NO3)2 and [PbCu5(picha)5(py)6](NO3)2 (axial pyridine molecules are not shown). Unlike the analogous lanthanide(III) derivatives, which are essentially flat, the presented 15‐metallacrown‐5 system is dome‐shaped, although not as convex as the shell of the turtle Gubi (shown in the background). Gubi is the favorite pet of the daughter of one of the authors. Details are discussed in the article by J. Lisowski et al. on p. 3015 ff.

Synthesis and Structural Characterisation of Copper(II) 15‐Metallacrown‐5 Complexes with PbII, HgII, AgI, NaI and YIII Central Metal Ions

“…In paramagnetic complexes with dominant dipolar and Curie relaxation mechanisms, the linewidths are inversely proportional to the sixth power of the proton-metal distance. [18] On this basis, the broadest and most-downfield-shifted 1 n+ complexes are very similar to those of the anal- [7,9] which is in accord with the dominant contact contribution to the isotropic (paramagnetic) shifts of the aminohydroximate ligand. The upfield paramagnetic shifts of the NH 2 protons probably reflect sizeable dipolar contributions to the isotropic shift or spin polarisation effects, [18] which lead to a different sign of the contact shift of the NH 2 protons relative to those of other ligand protons.…”

“…The Pb II ion adopts a pentagonal-pyramidal geometry, which is similar to that observed in a related nickel(II) 15-metallacrown-5 complex. [9] This geometry is relatively rare for lead(II) complexes. [12,13] The arrangement of the donor atoms around the Pb II ion is hemi-directed, in accord with the presence of the stereochemically active lone pair of electrons.…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) which the peripheral Cu II ions are replaced by Ni II ions [9] or the α-aminohydroximate ligand is replaced by mandelohydroximate [10] ( Figure 2) are also known. The high stability and preferred binding of UO 2 2+ over Ca 2+ by the copper(II) 15-metallacrown-5 complexes were studied in the context of the sequestering of the toxic uranyl ions and the biological importance of hydroxamic acids.…”

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

“…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. 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.…”

A Family of 12‐Azametallacrown‐4 Structural Motif with Heterometallic MnIII‐Ln‐MnIII‐Ln (Ln=Dy, Er, Yb, Tb, Y) Alternate Arrangement and Single‐Molecule Magnet Behavior

“…In the first case, 3d ions occupy MC ring sites with the cavities encapsulating 4f ions, and the ligands involve different organic hydroximic acids. Most of these MCs represent the 15‐MC‐5 structural type, mainly with Cu ions as ring metal ions,5c, 6 and only several cases displayed Ni ions in MC rings 7. Interestingly, 15‐MC‐5 complexes usually exhibited guest‐molecule recognition5c, 8 or served as building blocks for one‐dimensional solids 9.…”