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

Abstract

AbstractThe new copper(II) 15‐metallacrown‐5 complexes with the central metal ions PbII, HgII, AgI, NaI and YIII, with the formula [MCu5L5]Xn {H2L is 2‐picolinehydroxamic acid or (S)‐phenylalaninehydroxamic acid and X– is NO3– or Cl–}, have been synthesised and characterised by NMR and UV/Vis spectroscopy, electrospray mass spectrometry and elemental analysis. The PbII‐ and HgII 15‐metallacrown‐5 complexes were obtained in the crystalline form as pyridine adducts [PbCu5(picha)5(py)6](NO3)2·3(py) and [HgCu5(picha)5(py)7](NO3)2·2(py) and their X‐ray crystal structures were determined. In both complexes, each peripheral CuII ion of the metallacrown is coordinated by one pyridine molecule bonded in the axial position. In the case of the PbII derivative, one additional axial pyridine molecule is bound to the central metal ion, while in the case of the HgII derivative, two axial pyridine ligands are bound to the central HgII ion. The relative stability of the copper(II) 15‐metallacrown‐5 complexes with various central metal ions was determined on the basis of competition reactions. The relative preference of the 15‐metallacrown‐5 system for the central metal ion follows the series NaI, AgI < lanthanide(III), HgII < PbII.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)