Synthesis and characterization of the first tetraazadiphenol macrocyclic dinickel(II) complex containing μ(O,O′)-nitrito-nitro-aqua ligands

A novel tetraazadiphenol macrocyclic dinickel(II) complex with μ(O,O′)-nitrito-nitro-aqua ligands [Ni2([22]-HMTADO)(μ-O2N)(NO2)(OH2)] 2 (H2[22]-HMTADO = 5,5,11,17,17,23-hexamethyl-3,7,15,19-tetraazatricyclo[19.3.1.19,13] hexacosa-1(25),2,7,9,11,13(26),14,19,21,23-decane-25,26-diol) has been synthesized and structurally characterized by a combination of analytical, spectroscopic, and crystallographic methods. The nickel(II) centers in the tetraazadiphenol macrocyclic complex are bridged by the two phenolate oxygens as well as by nitrite ion and coordinated to nitro or aqua ligand, forming distorted octahedral geometries. The nonbonded Ni⋯Ni intermetallic separation in the complex 2 is 3.013 Å. In addition, the weak inter- and intra-molecular hydrogen-bonding interactions link these monomeric units into a three-dimensional supramolecular architecture.