Three transition-metal complexes with the macrocyclic ligand meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (L): [Cu(ClO₄)₂(L)], [Zn(NO₃)₂(L)] and [CuCl(L)(H₂O)]Cl.

The three transition-metal complexes, (meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-κ⁴N)bis(perchlorato-κO)copper(II), [Cu(ClO₄)₂(C₁₈H₄₀N₄)], (I), (meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-κ⁴N)bis(nitrato-κO)zinc(II), [Zn(NO₃)₂(C₁₈H₄₀N₄)], (II), and aquachlorido(meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-κ⁴N)copper(II) chloride, [CuCl(C₁₈H₄₀N₄)(H₂O)]Cl, (III), are described. The molecules display a very similarly distorted 4+2 octahedral environment for the cation [located at an inversion centre in (I) and (II)], defined by the macrocycle N₄ group in the equatorial sites and two further ligands in trans-axial positions [two O-ClO₃ ligands in (I), two O-NO₂ ligands in (II) and one chloride and one aqua ligand in (III)]. The most significant difference in molecular shape resides in these axial ligands, the effect of which on the intra- and intermolecular hydrogen bonding is discussed. In the case of (I), all strong hydrogen-bond donors are saturated in intramolecular interactions, while weak intermolecular C-H∙∙∙O contacts result in a three-dimensional network. In (II) and (III), instead, there are N-H and O-H donors left over for intermolecular interactions, giving rise to the formation of strongly linked but weakly interacting chains.