The Role of the C–H···π Interactions in the Cyclisation Reactions Leading to New Aryl-Bridged Tetraazamacrocyclic Complexes of Copper and Nickel

A series of neutral macrocyclic transition metal complexes of CuII and NiII, with bridging polyether linkers joining them to aromatic fragments, has been synthesised and their crystal and molecular structures have been established by single-crystal X-ray diffraction. These molecules adopt an “equatorial” conformation of the bridge due to formation of C–H···π interactions. Because of these interactions only cyclic products are formed in the SN2 reaction. DFT calculations also confirm experimental results.