1,1′-Biadamantane-3,3′-diol: a two-dimensional network supported by a `hexa­meric alcohol cluster' supra­molecular synthon

In the title compound, C₂₀H₃₀O₂, one of the two crystallographically independent mol­ecules lies across a centre of inversion and the other resides in a general position (Z′ = 1.5). The supra­molecular structure exists as an unusual two-dimensional network incorporating centrosymmetric hexa­meric hydrogen-bonded alcohol (OH)₆ clusters [O...O = 2.6637 (12)–2.6993 (12) Å] as the net nodes. The hexa­mers adopt a chair conformation [O...O...O = 106.55 (4)–115.81 (4)°] and are connected into a network with a square-grid topology (4⁴) by a combination of single and double 1,1′-biadamantanediyl links. The bulky aliphatic groups appear to require specific hexa­gonal packing and so generate distinct noncovalent hydro­phobic layers, which are essential for the stabilization of the hexa­meric alcohol array rather than the formation of the more commonly encountered tetra­mer-based arrays.

Cadmium(II) iodide and thio­cyanate complexes adopted by polycyclic 1,4-bis­(pyridazin-4-yl)benzene: inter­play of coordination and [pi]-[pi] stacking inter­actions

New complexes containing the 1,4-bis­(pyridazin-4-yl)­benzene ligand, namely diaqua­tetra­kis­[1,4-bis­(pyridazin-4-yl)­benzene-[kappa]N²]cadmium(II) hexa­iodido­dicadmate(II), [Cd(C₁₄H₁₀N₄)₄(H₂O)₂][Cd₂I₆], (I), and poly[[[mu]-1,4-bis­(pyridazin-4-yl)benzene-[kappa]²N²:N^2']bis­([mu]-thio­cyanato-[kappa]²N:S)­cadmium(II)], [Cd(NCS)₂(C₁₄H₁₀N₄)]_n, (II), demonstrate the adaptability of the coordination geometries towards the demands of slipped [pi]-[pi] 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-H...N^2' hydrogen bonding [O...N = 2.748 (4) and 2.765 (4) Å] and extensive triple [pi]-[pi] 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 Cd^II 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([mu]-NCS)₂]_n chains [Cd-N = 2.3004 (14) Å and Cd-S = 2.7804 (5) Å] with N²:N^2'-bident­ate organic bridges [Cd-N = 2.3893 (12) Å], which generate [pi]-[pi] stacks by double-slipped inter­actions between phenyl­ene and pyridazine rings [CCD = 3.721 (2) Å].

Cobalt(II) and cadmium(II) square grids supported with 4,4′-bipyrazole and accommodating 3-carb­oxy­adamantane-1-carboxyl­ate

In poly[[bis­(μ-4,4′-bi-1H-pyrazole-κ²N²:N^2′)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 [N...O = 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 [O...O = 2.565 (3) and 2.616 (3) Å] to the carboxylate groups in the next layer [O...O = 2.717 (3)–2.841 (3) Å], thereby extending the structures in the third dimension.

Multiple anion...π inter­actions in tris­(1,10-phenanthroline-κ²N,N′)iron(II) bis­[1,1,3,3-tetra­cyano-2-(2-hydroxy­ethyl)propenide] mono­hydrate

Double nitrile...π interactions are relevant for the crystal packing of charge-diffuse conjugated tetracyanopropenide anions when combined with common heteroaromatic tris-chelate octahedral complexes, [Fe(phen)₃]²⁻.