Adducts of 1,4,8,11-tetraazacyclotetradecane with carboxylic acids: hydrogen-bonded supramolecular structures in two or three dimensions.

Abstract

Four solvated salt-type adducts derived from cyclam (1,4,8,11-tetraazacyclotetradecane) and carboxylic acids have been structurally characterized. In the salt derived from adamantane-1-carboxylic acid, 4,11-diaza-1,8-diazoniacyclotetradecane bis(adamantane-1-carboxylate) tetrahydrate, (1) (monoclinic, P2(1)/c, Z' = 0.5), where the cation lies across a centre of inversion, the anions and the water molecules form chains of edge-fused R(4)(2)(8) and R(6)(6)(16) rings, which are linked into sheets by the cations. In the 4-aminobenzoate salt, 4,11-diaza-1,8-diazoniacyclotetradecane bis(4-aminobenzoate) monohydrate, (2) (monoclinic, C2/c, Z' = 0.5), where the cation lies across a centre of inversion and the water molecule lies across a twofold rotation axis, the cations and anions generate a three-dimensional framework, readily analysed in terms of two distinct two-dimensional substructures, viz. (10;1) sheets of R(8)(6)(46) rings, and pairwise interwoven (100) sheets, reinforced by water molecules. The 3-hydroxybenzoate salt, 4,11-diaza-1,8-diazoniacyclotetradecane bis(3-hydroxybenzoate) dihydrate, (3) (monoclinic, Pc, Z' = 1), contains a three-dimensional framework constructed from anions and water molecules only, which encapsulates large voids and within which the cations are linked to the anion-water framework via N-H.O hydrogen bonds. There are two independent cations in 4,11-diaza-1,8-diazoniacyclotetradecane 5-hydroxyisophthalate(2-) methanol solvate, (4) (monoclinic, P2(1)/c, Z' = 1), both lying across centres of inversion but with entirely different configurations. The anions alone form simple chains, and these chains are linked by the two types of cation into a three-dimensional framework from which the methanol molecules are pendent. Comparisons are made with carboxylate complexes of the [Ni(cyclam)](2+) cation and with carboxylate salts derived from meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane.