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Electrochemical Examination of Mixed‐Ligand Cobalt(III) Complexes with Tetraazamacrocyclic Ligand and Heterocyclic Dithiocarbamates
Author(s) -
Jovanović V. M.,
BabićSamardžija K.,
Sovilj S. P.
Publication year - 2001
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200109)13:13<1129::aid-elan1129>3.0.co;2-k
Subject(s) - cyclam , chemistry , piperazine , morpholine , piperidine , electrochemistry , ligand (biochemistry) , aqueous solution , cobalt , redox , inorganic chemistry , dithiocarbamate , heteroatom , cyclic voltammetry , medicinal chemistry , organic chemistry , ring (chemistry) , electrode , metal , biochemistry , receptor
Electrochemical stability of eight complexes of the general formula [Co III Rdtc(1–8)cyclam](ClO 4 ) 2 , where cyclam=1,4,8,11‐tetraazacyclotetradecane and Rdtc − (1–8)=4‐morpholine (Morphdtc), 4‐thiomorpholine (Timdtc), 4‐piperazine (Pzdtc), N ‐methyl piperazine ( N ‐Mepzdtc), piperidine (Pipdtc), 2‐, 3‐ or 4‐methylpiperidine (2‐, 3‐ or 4‐Mepipdtc) dithiocarbamates, respectively, were studied. The substances were examined in aqueous NaClO 4 solution and nonaqueous LiClO 4 in CH 3 CN solution by cyclic voltammetry. In aqueous solution, macrocyclic ligand cyclam is characterized by the anodic peak at 0.95 V. The Rdtc − ligands have two anodic peaks, one in the region 0.25–0.30 V and the other in the 0.78–0.95 V region. Absence of these anodic peaks in the case of the complexes indicates that coordination to cobalt(III) stabilizes both cyclam and Rdtc − ligands, but reversible peaks in the range −0.68 to −0.78 V support the Co(III) redox reaction. In nonaqueous solutions cyclam has one anodic peak at 1.75 V. The ligands with heteroatom in the ring (Morphdtc, Timdtc, Pzdtc, N ‐Mepzdtc) have two anodic peaks, while the other four ligands (Pipdtc, 2‐, 3‐ and 4‐Mepipdtc) have only one anodic peak. In nonaqueous solution again, coordination to Co(III) ion stabilizes the Rdtc − ligands and contrary to aqueous solution no Co(III) redox reaction occurs, indicating a greater stability of the complexes in this media. Finally, the electrochemical results are compared with spectroscopic data obtained previously.