Molecular structure in correlation with electrochemical properties of mixed-ligand cobalt(III) complexes

Abstract

Four mixed-ligand cobalt(III) complexes (1-4) of the general formula [Co(Rdtc)cyclam](ClO4)2 and [Co(Rac)cyclam](ClO4)2 (cyclam = 1,4,8,11-tetra- azacyclotetradecane; Rdtc = thiomorpholine-(Timdtc) or 2-methylpiperidine-(2-Mepipdtc) dithiocarbamates; Rac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato (Hfac) or 2,2,6,6-tetramethyl-3,5-heptanedionato (Tmhd), respectively) were electrochemically examined on a glassy carbon and an iron electrode in perchloric acid solution. The obtained results showed the influence of these complexes on hydrogen evolution, the oxygen reduction reaction and iron dissolution. The exhibited effects of the complexes on these reactions depend on structure related to the bidentate dithiocarbamato or b-diketonato ligand. The electrochemical properties of the complexes were correlated with molecular structure and parameters derived from spectral analysis and molecular modeling.

Četiri mešovito-ligandna kobalt(III) kompleksa opšte formule [Co(Rdtc)cyclam](ClO4)2 i [Co(Rac)cyclam](ClO4)2 (cyclam = 1,4,8,11-tetraazaciklotetradekan; Rdtc = tiomorfolin--(timdtc) ili 2-metilpiperidin-(2-mepipdtc) ditiokarbamat; Rac = 1,1,1,5,5,5-heksafluoro- -2,4-pentanedionato (hfac) ili 2,2,6,6-tetrametil-3,5-heptanedionato (tmhd)) ispitana su elektrohemijski na elektrodama od staklastog ugljenika i gvožđa u rastvoru perhlorata. Dobijeni rezultati ukazuju na to da ovi kompleksi utiču na izdvajanje vodonika, redukciju kiseonika kao i na rastvaranje gvožđa. Elektrohemijsko ponašanje zavisi od strukture koordinovanog bidentatnog ditiokarbamato ili b-diketonato liganda. Molekulska struktura kompleksnih jedinjenja određena je na osnovu spektroskopskih analiza i molekulskog modelovanja. Elektrokatalitički i inhibitorski efekat povezan je sa molekulskom strukturom kompleksa.