Synthesis and Characterization of New <i>trans</i> <i>N</i> , <i>N</i> ′-Disubstituted Macrocyclic “tet <i>a</i> ” Ligands and Their Copper(II) and Nickel(II) Complexes: Structural, Electrochemical, Magnetic, and Catalytic StudiesSengottuvelan, Nallathambi; Saravanakumar, Duraisamy; Narayanan, Vengidusamy; Kandaswamy, Muthusamy; Chinnakali, Kandaswamy; Senthilkumar, Gopal · Bulletin of the Chemical Society of Japan · 2004