A large number of complexes of tetraaza macrocyclic ligands is known. These ligands have from 12 to 16 atoms in the ring, and the most common structure is a 14-membered ring. The simplest of the ligands is 1,4,8,1 l-tetraazacyclotetradecane :A variety of metal complexes of this ligand have been prepared, including the metals C O ,~ Ni,2 and Rh.3 Coordination is generally in a planar fashion, although cis coordination to CO(III)~ has been reported. These complexes were first prepared by direct interaction of the ligand with the metal salt. Unfortunately, this ligand, unlike others of its class,5 has previously been available only through laborious organic syntheses.V Recently an in situ preparation of the nickel(I1) complex was reported.7 The ligand can easily be removed from the nickel(I1) and used in the preparation of other metal complexes.Given here is an improved version of this in situ synthesis which provides high yields of the nickel(I1) perchlorate complex. Procedures for removing the ligand from the metal and for its purification are also given.
Crystal Structure of a Monoazide Bridged Dimer of Ni(vV-tetramethylcyclam)2+Sir:Recently we reported the preparations of 1 and some of its metal complexes.1 A surprising and disappointing property of these complexes was their lability, which was apparently a result of the set of nitrogen donor configurations that was dictated by the kinetic precesses (1) E.
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