Syntheses and structures of two coordination polymers formed by Ni(cyclam)2+ cations and sulfate anions

Abstract

The coordination polyhedra of the complex cations in the one-dimensional title coordination polymers represent tetra­gonally distorted trans-NiN₄O₂ octa­hedra with the four N atoms of the macrocyclic ligand forming the equatorial plane and two O atoms of the sulfate anions occupying the axial positions.

The asymmetric units of catena-poly[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ⁴N¹,N⁴,N⁸,N¹¹)nickel(II)]-μ₂-sulfato-κ²O³:O⁴], [Ni(SO₄)(C₁₀H₂₄N₄)]_n (I), and catena-poly[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ⁴N¹,N⁴,N⁸,N¹¹)nickel(II)]-μ₂-sul­fato-κ²O³:O⁴] hemi[4,4′,4′′,4′′′-(2,2′,4,4′,6,6′-hexa­methyl-[1,1′-biphen­yl]-3,3′,5,5′-tetra­yl)tetra­benzoic acid] nona­hydrate], {[Ni(SO₄)(C₁₀H₂₄N₄)]₂·C₄₆H₃₈O₈·18H₂O}_n (II), consist of two crystallographically unique centrosymmetric macrocyclic dications and a sulfate dianion. In II it includes additionally a mol­ecule of the undissociated acid (2,2′,4,4′,6,6′-hexa­meth­yl[1,1′-biphen­yl]-3,3′,5,5′-tetra­yl)tetra­(benzoic acid) located on a crystallographic twofold axis and nine highly disordered water mol­ecules of crystallization. In both compounds, the metal ions are coordinated in the equatorial plane by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetic­ally stable trans-III conformation. Two O atoms of the sulfate anions occupy the trans-axial positions resulting in a slightly tetra­gonally distorted trans-NiN₄O₂ octa­hedral coordination geometry. The crystals of both compounds are composed of parallel coordination polymeric chains running along the [101] and [100] directions in I and II, respectively. The distances between the neighboring metal ions in the chains are significantly different [6.5121 (6) Å in I and 6.0649 (3) Å in II] and this peculiarity is explained by the different spatial directivity of the Ni—O coordination bonds (different S—O—Ni angles). As a result of the C—H⋯O hydrogen bonds between the methyl­ene groups of the macrocyclic ligands and the non-coordinated O atoms of the sulfate anion, the coordination-polymeric chains in I are arranged in the two-dimensional layers oriented parallel to the (010) and (101) planes, the inter­section of which provides the three-dimensional coherence of the crystals. The three-dimensional supra­molecular structure of the crystals II is determined by the network of strong hydrogen bonds formed by the carb­oxy­lic acid and the non-coordinated O atoms of the sulfate anions.