Cu(II) Compounds with Pyrimidine-Based Chelating Ligands, Bridged by a Flexible Alkyl Spacer: Synthesis, Characterisation and X-Ray Structures of Methoxide-Bridged Dinuclear-Based Species

Abstract

The synthesis and full structural characterisation is described of 3 dinuclear-based Cu(II) compounds bridged by methoxide anions, and flexible linear bis(pyrimidine)-α,ω-diaminoalkane ligands. The structures are dinuclear based in all cases, in which the bis(pyrimidine)diaminoalkane ligand chelates to 2 Cu(II) ions in the same dinuclear unit (N–C–C–C–C–C–N linker), or to two different dinuclear units (with the short N–C–C–N linker), thereby generating a polymeric chain. The magnetic exchange in the compounds is dominated by the alkoxido-bridged ligands, which generate a very strong antiferromagnetic coupling between the Cu(II) ions, resulting in diamagnetism at room temperature and below, and EPR silent behaviour. Dinuclear-based Cu(II) compounds with pyrimidine-based chelating ligands flexible linear bis(pyrimidine)-α,ω-diaminoalkane ligands are described, bridged by methoxide anions. The structures are dinuclear based in all cases, with the ligand chelating to 2 Cu(II) ions in the same dinuclear unit (N–C–C–C–C–C–N linker), or to 2 different dinuclear units (with short N–C–C–N linkers). The very strong antiferromagnetic magnetic exchange in all compounds is caused by the alkoxido-bridged ligands.