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Cobalt(II) Complexes with Nitrogen Donors and Their Dioxygen Affinity in Dimethyl Sulfoxide
Author(s) -
Comuzzi Clara,
Melchior Andrea,
Polese Pierluigi,
Portanova Roberto,
Tolazzi Marilena
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200208)2002:8<2194::aid-ejic2194>3.0.co;2-t
Subject(s) - chemistry , ethylenediamine , denticity , dimethyl sulfoxide , steric effects , adduct , electrochemistry , cobalt , standard enthalpy of formation , medicinal chemistry , sulfoxide , ionic bonding , enthalpy , inorganic chemistry , diamine , solvent , polymer chemistry , metal , stereochemistry , organic chemistry , ion , electrode , physics , quantum mechanics
The formation of Co II complexes with differently methylated N‐donor ligands ethylenediamine (en), N , N′ ‐dimethylethylenediamine (dmen), N,N , N′ ‐trimethylethylenediamine (trmen), and N , N , N′ , N′ ‐tetramethylethylenediamine (tmen), has been studied at 298 K in both the aprotic solvent dimethyl sulfoxide (dmso) and in an ionic medium set to 0.1 mol dm −3 with Et 4 NClO 4 under anaerobic conditions. UV/Vis spectrophotometric and calorimetric measurements were carried out to obtain the thermodynamic parameters for the systems investigated. Only mononuclear CoL j 2+ complexes were formed ( j = 1−3 for en, j = 1, 2 for dmen; and j = 1 for trmen and tmen) where the diamines act as bidentate agents. All the complexes are enthalpy‐stabilized whereas the entropy changes counteract the complex formation. The results are discussed in terms of different basicities and steric requirements both of the ligands and the complexes formed. Voltammetric measurements were carried out to correlate the electrochemical properties of the anaerobic complexes with their different dioxygen affinities. The X‐ray structure of the starting adduct [Co(dmso) 6 ][ClO 4 ] 2 , determined on a monocrystal, is also reported. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)