SYNTHESIS, CHARACTERIZATION AND CRYSTAL-STRUCTURE OF 2-AMINOPYRIDINIUM (2-AMINO-5-BROMOPYRIDINE)TRIBROMOCUPRATE(II) AND BIS(2-AMINOPYRIDINIUM) TETRABROMOCUPRATE(II)

2-Aminopyridinium (2-amino-5-bromopyridine)tribromocuprate(II) 1 and b is(2-aminopyridinium) tetrabromocuprate(II) 2 have been prepared from acetonitrile solutions containing CuBr2, HBr and 2-aminopyridine in 1: 2:2 and 1:2:1 molar ratio, respectively. The mother-liquor of 1 was ph otoirradiated with a superhigh-pressure mercury lamp and the organic b ase underwent partial electrophilic para bromination of the substitute d pyridine ring. The compounds have been characterised by elemental an alysis, IR, UV/VIS and ESR spectroscopies, thermal analysis, variable- temperature magnetic susceptibility measurements and single-crystal X- ray diffraction. The crystal structure of 1 consists of infinite zigza g chains of [C5H7N2](+) cations and distorted [CuBr3(C5H5BrN2)](-) tet rahedral anions running along the b axis and held together by means of N-H ... Br hydrogen contacts and non-covalent interactions between th e pi systems of the pyridine rings. In 2 organic cations and flattened [CuBr4](2-) anions form two-dimensional N-H ... Br hydrogen-bonded sh eets which are connected by electrostatic interactions, van der Waals forces and face-to-face stacking interactions between the pi systems o f the aromatic cations. Magnetic susceptibility measurements of powder ed samples showed that both compounds exhibit weak antiferromagnetic e xchange interactions [J = -1.20 (1), -2.43 cm(-1) (2)]. Thermal decomp osition of both compounds yielded copper(II) oxide and metallic Cu as stable final residues in synthetic air and dinitrogen atmospheres, res pectively.