Crystal structure of bis(4-dimethylaminopyridinium) tribromocuprate(I) and bis(4-dimethylaminopyridinium) tetrabromocuprate(II)

The synthesis and crystal structures of two copper bromide salts of the 4-dimethylaminopyridinium (4DMAP⁺) cation are reported. The Cu(I) salt, (4DMAP)₂CuBr₃, crystallizes in the monoclinic space group C2/c, with a = 11.724(2), b = 11.055(3), c = 15.763(3) Å, = 107.64(3)°, and Z = 4. It contains isolated planar 4DMAP⁺ cations and trigonal planar CuBr₃ ^2– anions. Small distortions from idealized D _3h symmetry are observed for the anion. For the Cu(II) salt, (4DMAP)₂CuBr₄, a triclinic cell is observed with a = 8.2373(2), b = 9.2428(2), c = 14.4391(1) Å, = 93.760(1), = 94.576(1), = 105.249(1)°, and Z = 2. This compound contains discrete planar 4DMAP⁺ cations and flattened tetrahedral CuBr₄ ^2– anions. Small distortions are observed for ideal D _2d symmetry.