Copper(II) bromide and copper(II) acetate complexes of 4,4'-(p-phenylene)bipyridazine.

4,4'-(p-Phenylene)bipyridazine, C(14)H(10)N(4), (I), and the coordination compounds catena-poly[[dibromidocopper(II)]-mu-4,4'-(p-phenylene)bipyridazine-kappa(2)N(2):N(2')], [CuBr(2)(C(14)H(10)N(4))](n), (II), and catena-poly[[[tetrakis(mu-acetato-kappa(2)O:O')dicopper(II)]-mu-4,4'-(p-phenylene)bipyridazine-kappa(2)N(1):N(1')] chloroform disolvate], {[Cu(2)(C(2)H(3)O(2))(4)(C(14)H(10)N(4))].2CHCl(3)}(n), (III), contain a new extended bitopic ligand. The combination of the p-phenylene spacer and the electron-deficient pyridazine rings precludes C-H...pi interactions between the lengthy aromatic molecules, which could be suited for the synthesis of open-framework coordination polymers. In (I), the molecules are situated across a center of inversion and display a set of very weak intermolecular C-H...N hydrogen bonds [3.399 (3) and 3.608 (2) A]. In (II) and (III), the ligand molecules are situated across a center of inversion and act as N(2),N(2')-bidentate [in (II)] and N(1),N(1')-bidentate [in (III)] long-distance bridges between the metal ions, leading to the formation of coordination chains [Cu-N = 2.005 (3) A in (II) and 2.199 (2) A in (III)]. In (II), the copper ion lies on a center of inversion and adopts CuN(2)Br(4) (4+2)-coordination involving two long axial Cu-Br bonds [3.2421 (4) A]. In (III), the copper ion has a tetragonal pyramidal CuO(4)N environment. The uncoordinated pyridazine N atom and two acetate O atoms provide a multiple acceptor site for accommodation of a chloroform solvent molecule by trifurcated hydrogen bonding [C-H...O(N) = 3.298 (5)-3.541 (4) A].