Halogen Bonding Channels for Magnetic Exchange in Cu(II) Complexes with 2,5-Di(methylthio)-1,3,4-thiadiazole.

Copper(II) complexes with 2,5-bis(methylthio)-1,3,4-thiadiazole (tda) formulated as [Cu(tda) n X 2 ] (n=2, X=Cl - , Br - , C 2 N 3 - ; n= 1, X=C 2 N 3 - ) have been isolated and fully characterized. The crystal structures of all compounds have been determined using single-crystal X-ray diffraction (SCXRD). A study of the magnetic susceptibility in the range 1.77-300 K has shown that magnetic properties of the [Cu(tda) 2 Cl 2 ] and [Cu(tda) 2 Br 2 ] complexes match those of 1D chains of antiferromagnetically-coupled Cu 2+ ions. The intrachain interaction J in [Cu(tda) 2 Cl 2 ] turns out to be ∼1.2 times weaker than in its bromide analogue. In its turn, [Cu(tda) 2 (C 2 N 3 ) 2 ] exhibits J being an order of magnitude smaller and of the opposite ferromagnetic sign. Halogen bonding (HB) between adjacent complexes is much stronger than the H-bonds or π-π interactions between tda ligands according to the DFT calculations.