Magnetic properties and molecular structure of a binuclear alternative bridged Cu(II)Re(IV) complex containing a macrocyclic ligand

Abstract

Two novel macrocyclic compounds, the heterobimetallic complex {(CuLα)[ReCl4(ox)]}n (1) and the mononuclear complex [CuLα]·2ClO4 (2) (where Lα=N-meso-5,12-Me2-7,14-Et2-[14]-4,11-dieneN4), have been synthesized and their crystal structures were determined by the single-crystal X-ray diffraction technique. Complex 1 crystallizes in the monoclinic space group P21/c, whereas 2 crystallizes in the monoclinic space group P21/n. The [CuLα]2+ macrocyclic cation in 1 is coordinated from above and below by [ReCl4(ox)]2− units through the chloro- and monodentate oxalato ligands, and this creates an alternating chloro-oxalato-bridged heterometallic ReIV–CuII one-dimensional zig-zag chain. Their magnetic measurements were carried out over the temperature range 1.8–300K using a Quantum Design SQUID magnetometer (MPMSxL-5 type). Compound 1 behaves like a ferrimagnetic CuII–ReIV dimetallic chain with two intrachain antiferromagnetic coupling parameters and strong single-ion anisotropy, D(Re)=109cm−1. Compound 2 shows weakly interacting paramagnetic centers in the crystal lattice. The effects of hydrogen bonds mediating the magnetic exchange interactions on the spin density have been evidenced by DFT calculations.