Discrete and 1D coordination polymeric chloro-bridged copper(II) dimers exhibiting ferro- and antiferromagnetic exchange coupling: Magneto-structural correlations and non-covalent interactions

The synthesis and characterization of two 1D coordination polymers [Cu-2(MHL)Cl-2][ClO4](2) center dot CH3CN center dot THF (2 center dot CH3CN center dot THF) and [Cu-2(MPyPz)Cl-2][ClO4](2) center dot CH3CN (3 center dot CH3CN), having repetitive {Cu-2(II)(mu-Cl)(2) units, of m-xylyl-based ligands with terminal tridentate (2-pyridyl) alkylamine (MHL = alpha, alpha'-bis[N-(2-pyridylethyl)-N-( 2-pyridylmethyl)amino]-m-xylene) and (2-pyridyl)alkylamine/pyrazole (MPyPz = alpha, alpha'-bis[N-(2-pyridylethyl)N-( pyrazol-1-ylmethyl)amino]-m-xylene) coordination have been accomplished. X-ray crystallographic studies reveal that the copper(II) centers in the recently reported dichloro-bridged discrete {Cu-2(II)(mu l-Cl)(2)} complex [{Cu(MeL)Cl}(2)][ClO4](2) (1) of a tridentate (2-pyridyl) alkylamine ligand [MeL = methyl[2-(2-pyridyl)ethyl](2-pyridylmethyl)amine], 2 center dot CH3CN center dot THF, and 3 center dot CH3CN have distorted square-pyramidal geometry, sharing a base-to-apex edge with parallel basal planes. Variable-temperature susceptibility measurements in the range of 2-300 K reveal antiferromagnetic for 1 [J/ (singlet-triplet energy gap) = -3.89 cm (1)] and 2 center dot CH3CN center dot THF (J = -1.84 cm (1)), and ferromagnetic for 3 center dot CH3CN (J = +6.27 cm (1)) coupling. The complexes provide useful information for the magneto-structural correlations. (c) 2008 Elsevier B.V. All rights reserved.