Spectroscopic studies of transition metal complexes with a N-donor tetradentate(N4) 12-membered macrocylic ligand

Chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), iridium(III), palladium(II) and platinum(II) complexes were synthesized with a 12-membered 1,4,7,10-tetraazadodeca-5,6,11,12-tetraene macrocylic ligand (L) and characterized by elemental analysis, molar conductance, magnetic susceptibility, IR, electronic, EPR and Mössbauer [Fe(III)] spectral studies. The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature for M(L)Cl2 complexes [where M = Mn(II), Co(II), Ni(II), Cu(II)], 1:1 electrolytes for M′(L)Cl3 complexes [where M′ = Cr(III), Fe(III), Ru(III) and Ir(III)] and 1:2 electrolytes for M″(L)Cl2 complexes [where M″ = Pd(II) and Pt(II)]. Thus, the complexes may be formulated as [M(L)C12], [M′(L)C12]C1 and [M″(L)]C12, respectively [where L = ligand]. All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Pd(II) and Pt(II) complexes which were four coordinate, square planar and diamagnetic.