Studies on mixed ligand complexes, part 5. Heterochelate complexes of cobalt(III) derived from the quadridentate NNNN donor ligand triethylenetetramine and bidentate OO, ON and NN donor ligands

Abstract

A series of new cobalt(III) complexes of general formula [Co(AA)(trien)]Xn (where AA = tropolone, acetoacetanilide, ethylacetoacetate, biguanide, 2-guanidinobenzimidazole, propylenediamine, picolylamine, 2,2′-dipyridyl, 3-aminopyridine, picolinic acid and quinaldinic acid, trien = triethylenetetramine, X=Cl−, Br−, I− and n=2–3) have been synthesized and characterized by elemental analysis, electronic and i.r. spectra, equivalent weight, conductance and magnetic measurements. The electronic spectra of the complexes exhibit one or two ligand field bands atca. 20000 and 29000 cm−1 due to the1A1g→1T1g and1A1g→1T2g transitions respectively. Conductance measurements indicate the triunivalent nature of [Co(tropolone)(trien)]I3, [Co(picolylamine)(trien)]I3, [Co(3-aminopyridine)(trien)]I3, [Co(2,2′-dipyridyl)(trien)]Cl3, [Co(biguanide)(trien)]I3, [Co(propylenediamine)(trien)]I3 and biunivalent nature of [Co(picolinate)(trien)]Cl2, [Co(quinaldinate)(trien)]Cl2, [Co(acetoacetanilido)(trien)]Cl2, and [Co(ethylacetoacetato)(trien)]I2. Equivalent weight determination by the ion-exchange resin (H+ form) method gives the values of molecular weights which are consistent with the theory. The complexes are diamagnetic.