Copper(II) Complexes of Two New Pyridyl–Aliphatic Amine Ligands: Synthetic, Structural, EPR, and Magnetic Studies

Abstract

Two new polyamine ligands, L1 and L2, incorporating pyridyl and aliphatic amine donor sites have been prepared and their reaction with copper(ii) yields the mono- and binuclear complexes [Cu(L1)](ClO4)2 (1) and [Cl2Cu(L2)CuCl(H2O)]ClO4 (2), respectively. The X-ray structure of 1 confirms that the five nitrogen donors of L1 are bound to the central copper ion to give a distorted square pyramidal coordination sphere. In 2, L2 acts as a bridging ligand with its N3-donor coordination domains separated by a m-xylylene spacer group. An unusual feature of this latter complex is that symmetrical L2 gives rise to non-equivalent coordination behaviour at the individual copper sites; while both sites display five-coordination with distorted square pyramidal arrangements, they differ in having N3Cl2- and N3ClO-donor atom sets, respectively. The electron paramagnetic resonance (EPR) spectra of both complexes are discussed. Variable temperature magnetic susceptibility data confirmed the absence of magnetic interactions in 1 while a weak antiferromagnetic interaction between copper(ii) centres occurs in 2.

Metal ion binding by pyridylethyl-containing polymers: experimental and theoretical study

“…The values found for A k and g k for Cu 2+ complexes with PEPAA and PEPEI are in good agreement with ESR parameters (Table 4) reported for Cu 2+ complexes with pyridyl-aliphatic amine ligands, for which the X-ray structure was determined to be a distorted square pyramid with the five-coordinated Cu 2+ ion. 44 It is worth mentioning that such five-coordinated complexes were earlier reported for Ni 2+ with chelating ligands containing imidazole-and pyridyl groups, 47 and for Cu 2+ and pentadentate ligands with pyridyl and amino groups. 48 In principle, one can assume Cu 2+ ion coordination via several pyridyl groups from different fragments of the PEC, PEPAA, and PEPEI chains.…”

“…However, aside from changes related to the properties of introduced functional groups, structural peculiarities of the precursor macromolecules and cross-linking make significant contribution to the sorption performance of modified polymers. 44 17.0 (110 K) 2.215 (110 K) 2.05 (110 K)…”