Discrete dinuclear metallo-macrocyclic complexes have been prepared from the flexible amide ligand N-6-[(3-pyridylmethylamino)carbonyl]pyridine-2-carboxylic acid (L1-CH3), and its more rigid analogue, N-6-[(3-pyridylamino)carbonyl]pyridine-2-carboxylic acid (L3-CH3). With ligands L1-CH3 and L3-CH3, discrete dinuclear metallo-macrocyclic complexes with the generic formula [Cu2(L1-CH3)2(X)2(Y)2] (7, X = NO3; 8, X = Cl, Y = H2O; 9, X = ClO4, Y = CH3OH) and [Cu2(L3-CH3)2(X)2(Y)2] (10, X = NO3, Y = H2O; 11, X = ClO4, Y = CH3OH) are obtained. For complexes 7–9, containing the more flexible link L1-CH3, these complexes are cleft-shaped and hinged at the methylene spacer, which allows the cleft to widen and contract to accommodate different packing modes in the solid-state. In contrast, the rigid link L3-CH3 gives near planar metallo-macrocyclic structures. These metallo-macrocyclic compounds may be useful building blocks for coordination polymers.
