Structure and magnetic characterization of some bicompartmental [N6O2] divalent metal(ii) complexes using bis(phenolato) ligands bearing two pendant bis(pyridyl) amine arms

Abstract

Reactions of the bicompartmental bis(phenolato) compound 6,6′-methylenebis(2-((bis(pyridin-2-ylmethyl)amino)methyl)-4-chlorophenol)hemihydrate (H₂L ½H₂O) with 3d metal(II) ions afforded novel fully structurally characterized bridged acetato dinuclear complexes [Mn₂(HL)(μ_1,2-OAc)₂]PF₆ (1) [Zn₂(HL)(μ_1,2-OAc)(H₂O)_0.75(MeOH)_0.25](PF₆)₂·0.45(H₂O) (5) and [Cd₂(HL)(μ_1,1,2-OAc)(OAc)(H₂O)]PF₆·H₂O (6) as well as the polymeric bridged-azido tetranuclear catena-[Cu₄(HL)₂(μ_1,1-N₃)₂(μ_1,3-N₃)₂](NO₃)₂·5H₂O (4). The complex [Cu₄(HL)₂(ClO₄)₃(H₂O)₅](ClO₄)₃·5H₂O (2) was partially characterized. In addition, three more dinuclear complexes [Cu₂(H₂L)(NO₃)₂(H₂O)₂](NO₃)₂ (3), [Cu₂(HL)(OAc)(CH₃OH)](PF₆)₂ (7) and [Cu₂(HL)(NCS)₂]NO₃·2H₂O (8) were also isolated. All complexes were characterized by CHN elemental analysis, IR and UV-Vis spectroscopy, ESI-MS, conductivity measurements and X-ray single crystal crystallography for compounds 1, 4, 5 and 6, where the bis(phenolato) ligand displayed different deprotonation (H₂L, HL⁻ and L²⁻). The magnetic susceptibility measurements over the temperature range 2–300 K revealed very weak antiferromagnetic coupling in dimanganese(II) 1 (J = −1.64(1) cm⁻¹) and almost negligible magnetic interaction in dicopper(II) 2 (J = 0(3) cm⁻¹). In the azido catena-[Cu₄(HL)₂(μ_1,1-N₃)₂(μ_1,3-N₃)₂](NO₃)₂·5H₂O (4) complex, the J value of −133(3) cm⁻¹ was obtained upon moderate-to-strong antiferromagnetic coupling through the di-μ_1,3-N₃-bridged dicopper(II) unit with no magnetic interaction between the two copper(II) ions in the di-μ_1,1-N₃-bridged unit.