Nickel(II) and copper(II) complexes of the macrocyclic ligand 5,7,7-Trimethyl-1,4,8,11-tetraazacyclotetradec-4-ene

Abstract

Nickel(II) and copper(II) complexes of 1,4,8,11-tetraazaundecane, (L), react with acetone, diacetone alcohol or mesityl oxide to form complexes of the macrocyclic ligand 5,7,7-trimethyl-1,4,8,11-tetra- azacyclotetradec-4-ene. For the nickel(II) cation, singlet ground state, square planar, salts are formed with poorly coordinating anions such as tetrachlorozincate, and triplet ground state, pseudoocta- hedral compounds with coordinating anions. These occur as trans compounds (macrocycle in planar coordination) for the unidentate anions NCS^-, N₃^- and Cl^- and as cis compounds (macrocycle in folded coordination)for the chelating anions acetylacetonate and oxalate. Different configurations of the chiral nitrogen centres are optimum for planar and for folded coordination of the macrocycle.