POLAROGRAPHIC BEHAVIOUR OF SOME COBALT(III) COMPLEXES WITH ETHYLENEDIAMINE

The polarographic behaviour of various cobalt(III)-amine complexes with ethylenediamine were studied in Britton-Robinson buffer solutions and also in the presence of 1,2-cyclohexane dione dioxime. It was observed that the cobalt(III)-amine complexes, generally, are reduced in two steps. The first wave (Co(III) -> Co(II)) has an irreversible character, the second one corresponds rather to a Co(II)-ligand -> Co(0) step, than to a . [Co(H20)6]2+ -> Co(0) reduction, as presumed earlier. In the presence of dioximes the hexamine and monoacidopentamine type cobalt(llI) complexes do not undergo substitution reactions under the above mentioned experimental conditions

ÜBER DIOXIMINKOMPLEXE DER ÜBERGANGSMETALLE. LXXX. KATALYTISCHE POLAROGRAPHISCHE REDUKTION VON HYDROXYLAMIN IN ANWESENHEIT VON EISEN(II)-DIOXIMINKOMPLEXEN

The stability constants of the iron(II)-nyoximine chelates: Fe(Nyox. H)* and Fe(Nyox. H)2 in aqueous NaClO4 -Britton-Robinson buffer solutions have been determined polarographi- cally. In the Fe(II)-nyoxime system appears a catalytic wave in the presence of hydroxylamine, with a half wave potential of -0.90 V (vs. SCE), suitable for the quantitative polarographic determination of hydroxylamine, also in the presence of hydrazine

ON THE DIOXIMINE COMPLEXES OF TRANSITION METALS. XCI. POLAROGRAPHIC STUDIES ON VARIOUS TYPES OF DIOXIMINE COMPLEXES OF COBALT(III)

The polarographic behaviour of some dioximine chelates of cobalt(III) (α-dioxime: Diox.H2, DH2-dimethylglyoxime, Nyox.H2=nyoxime, Heptox.H2=heptoxime ):[Co(DH)2 (amine)2]+, [Co(Nyox.H)2(amine)2]+, [Co(Diox.H)2XY]-(X, Y=Cl, Br, I, N02, N3, CN), [Co(DH)2(S03)(amine)]-, (alkyl-Co(DH)2 (amine) were studied at various pH-values (cathodic reductions and in some cases also anodic oxidations). The Co(II)-nyoxime system and the formation of [Co(Diox.H)2en]- by the substitution reactions of 1,2- and 1,6-[Co(en)2CI2]+ and [Co(en)CI(H20)]2+ with α-dioximes were studied in this way