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[Ni(cyclam)(OCOR)2], a finite molecular complex: hydrogen-bonded supramolecular aggregation in one, two and three
Choudhury M Zakaria1, George Ferguson, Alan J Lough
1School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, Scotland.
Abstract:
In the complexes [Ni(cyclam)(OCOR)2] (cyclam = 1,4,8,11-tetraazacyclotetradecane), where (RCOO)- is 2-naphthoate [bis-(2-naphthoato)-1,4,8,11-tetraazacyclotetradecanenickel(II), (I), monoclinic P2(1)/c, Z' = 0.5], 3,5-dinitrobenzoate [bis-(3,5-dinitrobenzoato)-1,4,8,11-tetraazacyclotetradecanenickel(II), (II), triclinic P1, Z' = 0.5], 4-nitrobenzoate [bis-(4-nitrobenzoato)-1,4,8,11-tetraazacyclotetradecanenickel(II), (III), monoclinic P2(1)/n, Z' = 0.5], 3-hydroxybenzoate [bis-(3-hydroxybenzoato)-1,4,8,11-tetraazacyclotetradecanenickel(II), (IV), monoclinic P2(1)/c, Z' = 0.5] and 4-aminobenzoate [bis-(4-aminobenzoato)-1,4,8,11-tetraazacyclotetradecanenickel(II), (V), monoclinic C2/c, Z' = 0.5], the Ni lies on a centre of inversion with monodentate carboxylato ligands occupying trans sites. Compound (I) consists of isolated molecules. In (II) and (III), N-H...O hydrogen bonds link the complexes into chains. Compounds (IV) and (III) form two- and three-dimensional structures generated entirely by hard hydrogen bonds. The 5-hydroxyisophthalate(2-) anion forms a hydrated complex, [Ni(cyclam)(5-hydroxyisophthalate)(H2O)]*4H2O [[aqua-(5-hydroxyisophthalato)-1,4,8,11-tetraazacyclotetradecanenickel(II)] tetrahydrate, (VI), monoclinic Cc, Z' = 1], in which the monodentate carboxylato ligand and a water molecule occupy trans sites at Ni: extensive hydrogen bonding links the molecular aggregates into a three-dimensional framework. The terephthalate(2-) anion forms a hydrated linear coordination polymer [catena-poly[terephthalato-1,4,8,11-tetraazacyclotetradecanenickel(II)] monohydrate, (VII), monoclinic C2/c, Z' = 0.5]. In 1,2,4,5-benzenecarboxylate tris[1,4,8,11-tetraazacyclotetradecanenickel(II)] diperchlorate hydrate (VIII), [Ni(cyclam)]3*[1,2,4,5-benzenetetracarboxylate(4-)]*[ClO4]2*[H2O]3, there are two distinct Ni sites: [Ni(cyclam)]2+ and centrosymmetric [C10H2O8]4- units form a two-dimensional coordination polymer, whose sheets are linked by centrosymmetric [Ni(cyclam)(H2O)2]2+ cations.