metal-organic compounds
New complexes containing the 1,4-bis(pyridazin-4-yl)benzene ligand, namely diaquatetrakis[1,4-bis(pyridazin-4-yl)benzene-N2]cadmium(II) hexaiodidodicadmate(II), [Cd(C14H10N4)4(H2O)2][Cd2I6], (I), and poly[[-1,4-bis(pyridazin-4-yl)benzene-2N2:N2']bis(-thiocyanato-2N:S)cadmium(II)], [Cd(NCS)2(C14H10N4)]n, (II), demonstrate the adaptability of the coordination geometries towards the demands of slipped - stacking interactions between the extended organic ligands. In (I), the discrete cationic [Cd-N = 2.408 (3) and 2.413 (3) Å] and anionic [Cd-I = 2.709 (2)-3.1201 (14) Å] entities are situated across centres of inversion. The cations associate via complementary O-HN2' hydrogen bonding [ON = 2.748 (4) and 2.765 (4) Å] and extensive triple - stacking interactions between pairs of pyridazine and phenylene rings [centroid-centroid distances (CCD) = 3.782 (4)-4.286 (3) Å] to yield two-dimensional square nets. The [Cd2I6]2- anions reside in channels generated by packing of successive nets. In (II), the CdII cation lies on a centre of inversion and the ligand is situated across a centre of inversion. A two-dimensional coordination array is formed by crosslinking of linear [Cd(-NCS)2]n chains [Cd-N = 2.3004 (14) Å and Cd-S = 2.7804 (5) Å] with N2:N2'-bidentate organic bridges [Cd-N = 2.3893 (12) Å], which generate - stacks by double-slipped interactions between phenylene and pyridazine rings [CCD = 3.721 (2) Å].
metal-organic compounds
In poly[[bis(μ-4,4′-bi-1H-pyrazole-κ2N2:N2′)bis(3-carboxyadamantane-1-carboxylato-κO1)cobalt(II)] dihydrate], {[Co(C12H15O4)2(C6H6N4)2]·2H2O}n, (I), the Co2+ cation lies on an inversion centre and the 4,4′-bipyrazole (4,4′-bpz) ligands are also situated across centres of inversion. In its non-isomorphous cadmium analogue, {[Cd(C12H15O4)2(C6H6N4)2]·2H2O}n, (II), the Cd2+ cation lies on a twofold axis. In both compounds, the metal cations adopt an octahedral coordination, with four pyrazole N atoms in the equatorial plane [Co—N = 2.156 (2) and 2.162 (2) Å; Cd—N = 2.298 (2) and 2.321 (2) Å] and two axial carboxylate O atoms [Co—O = 2.1547 (18) Å and Cd—O = 2.347 (2) Å]. In both structures, interligand hydrogen bonding [NO = 2.682 (3)–2.819 (3) Å] is essential for stabilization of the MN4O2 environment with its unusually high (for bulky adamantanecarboxylates) number of coordinated N-donor co-ligands. The compounds adopt two-dimensional coordination connectivities and exist as square-grid [M(4,4′-bpz)2]n networks accommodating monodentate carboxylate ligands. The interlayer linkage is provided by hydrogen bonds from the carboxylic acid groups via the solvent water molecules [OO = 2.565 (3) and 2.616 (3) Å] to the carboxylate groups in the next layer [OO = 2.717 (3)–2.841 (3) Å], thereby extending the structures in the third dimension.