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)(2)Cu2Br6 (1), (3,5-diBAPH)(2)Cu2Cl6 (2) and (3,5-diBAPH)(2)Cu2Br6 (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, P2(1)/c) and exhibit alternating layers of hexahalodicuprate ions and organic cations. The hexahalodicuprate ions exhibit short X center dot center dot center dot Cu and X center dot center dot center dot 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. [GRAPHICS]