Reaction of [M(ppn)2]X2 (where M = Cu(II), Ni(II), Co(II) and ppn = 1,3-diaminopropane) with formaldehyde and ethylenediamine in methanol results in the ready formation of a 16-membered macrocyclic complex. The complexes were characterized by elemental analysis, IR, EPR, electronic spectral data magnetic moments and conductance measurements. The Cu(II), Ni(II) and Co(III) complexes are coordinated axially with both pendant groups of the hexadentate macrocycle. These pendant donors are attached to the macrocycle by a carbon chain. The electrical conductivities of the Cu(II) and Ni(II) chelates indicated them to be 1:2 electrolytes whilst those of Co(III) is a 1:3 electrolyte in DMSO. The EPR spectrum of the copper complex exhibited G at 3.66, which indicates a considerable exchange interaction in the complex. Spectroscopic evidence suggests that in all of the complexes the metal ion is in an octahedral environment.

Heterotrinuclear complexes of the type [Cu(ppn) 2 Cl 2 fTi(Cp) 2 g 2 ] and [Cu(en) 2 (NO 3 ) 2 fTi(Cp) 2 g 2 ] have been synthesized and characterized by elemental analyses, IR, electronic, EPR, and 1 H NMR spectra, magnetic moments, and conductivity measurements. The results indicate that the trinuclear complexes are covalent with an octahedral environment around the copper(II) ion, while its mononuclear analogues, [Cu(ppn-H 2 ) 2 ]Cl 2 and [Cu(en-H 2 ) 2 ](NO 3 ) 2 , are square-planar and ionic in nature.

ABSTRACT. Tetraaza Schiff base macrocyclic ligands, L 1 ,L 2 and their transition metal chelates have been synthesized and characterized by elemental analyses, IR, electronic, EPR and 1 H NMR spectra, TGA and magnetic measurements. The molar conductance of one milli-molar solution of the complexes measured in DMF indicates that the divalent metal complexes are nonelectrolyte while those of trivalent metal ion, are 1:1 electrolytic in the same solvent. The reduction of Racah parameter from the free ion value confirms the presence of considerable covalence of metal ligand sigma bond in the Co(II) and Mn(II) complexes. The EPR spectra of Cu(II) complexes at room temperature shows axial symmetry indicating a dx 2 -y 2 ground state with significant covalent character. The thermal analysis suggests that the complexes do not contain water molecules because only the metal is left as residue.

Two isomers of [Cu(dien)Cl 2 ] of two different colours (blue and yellow), where dien ¼ diethylenetriamine have been isolated. They have been synthesized by a slight variation in the procedure. Both complexes turn blue in aqueous, ethanolic and DMSO solutions and attain a stable geometry. The blue isomer is thermally more stable than the yellow one. Both of them have identical electronic spectra and 1 values in solution.

Four novel N 4 -type macrocyclic chelating agents L 1 , L 2 , L 3 , L 4 with pendant groups and their metal chelates with some transition metal ions have been synthesized. Electrical conductance of the Cr(III) and Fe(III) chelates indicated them to be 1:1 electrolytes whilst those of divalent metal ions are non-electrolytes in DMSO. Spectroscopic evidence suggests that all of the complexes are six-coordinate and the pendant groups are not involved in coordination.