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-κ(2)N(2):N(2'))bis(3-carboxyadamantane-1-carboxylato-κO(1))cobalt(II)] dihydrate], {[Co(C12H15O4)2(C6H6N4)2]·2H2O}n, (I), the Co(2+) 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 Cd(2+) 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) Šand 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.

catena-Poly[thorium(IV)-tetrakis(µ(2)-3-carboxyadamantane-1-carboxylato)]: a quadruple helical strand driven by a synergy of coordination and hydrogen bonding.

The title compound, [Th(C(12)H(15)O(4))(4)](n), is the first homoleptic thorium-carboxylate coordination polymer. It has a one-dimensional structure supported by the bidentate bridging coordination of the singly charged 3-carboxyadamantane-1-carboxylate (HADC(-)) anions. The metal ion is situated on a fourfold axis (site symmetry 4) and possesses a square-antiprismatic ThO(8) coordination, including four bonds to anionic carboxylate groups [Th-O = 2.359 (2) Å] and four to neutral carboxyl groups [Th-O = 2.426 (2) Å], while a strong hydrogen bond between these two kinds of O-atom donor [O...O = 2.494 (3) Å] affords planar pseudo-chelated Th{CO(2)...HO(2)C} cycles. This combination of coordination and hydrogen bonding is responsible for the generation of quadruple helical strands of HADC(-) ligands, which are wrapped around a linear chain of Th(IV) ions [Th...Th = 7.5240 (4) Å] defining the helical axis.