Transition metal salts of 2-amino-3,5-dihalopyridine - dimers: syntheses, structures and magnetic properties of (3,5-diCAPH)₂Cu₂Br₆ and (3,5-diBAPH)₂Cu₂X₆

Three dimeric copper(II) complexes have been prepared with the general formula bis(2-amino-3,5-dihalopyridinium)hexahalodicuprate cuprate(II): (3,5-diCAPH)₂Cu₂Br₆ (1), (3,5-diBAPH)₂Cu₂Cl₆ (2) and (3,5-diBAPH)₂Cu₂Br₆ (3) [3,5-diCAPH = 2-amino-3,5-dichloropyridinium; 3,5-diBAPH = 2-amino-3,5-dibromopyridinium]. The compounds have been characterized via single crystal X-ray diffraction and temperature dependent magnetic susceptibility measurements. All three compounds crystallize in monoclinic space groups (1, C2/c; 2 and 3, P2₁/c) and exhibit alternating layers of hexahalodicuprate ions and organic cations. The hexahalodicuprate ions exhibit short X⋯Cu and X⋯X contacts which link the dimers into a square array. Variable temperature magnetic susceptibility data reveal strong intradimer antiferromagnetic exchange (J = −153, −65, −122 K for 1–3, respectively), but negligible inter-dimer magnetic exchange.