Thermodynamic studies on the complexation of cobalt(II) with nitrogen donor ligands in dimethyl sulfoxide

Comuzzi, Clara; Grespan, Michela; Polese, Pierluigi; Portanova, Roberto; Tolazzi, Marilena

doi:10.1016/s0020-1693(01)00513-8

Cited by 17 publications

(31 citation statements)

References 31 publications

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“…A more dramatic decrease in the stability constant is observed when the formation of the bis-ligand complexes of dmdien (logK 2 3.67) and dien (logK 2 5.90) [24] are compared. This matches the result obtained for the same triamines in DMSO, where a lower stability ( Table 1) and a less exothermic value for the complexation reaction was also measured in going from dien to dmdien [14]. The lower complexation ability of the N-methylated dmdien with respect to dien has been attributed to a minor strength of the MÀN bonds due to both the decreased basicity of the N-atoms and the steric crowding produced by the N-alkyl groups, which causes an elongation of MÀN bonds [18].…”

supporting

confidence: 90%

Section: Experimental Partmentioning

confidence: 99%

“…[Co(ClO 4 ) 2 ]´6 DMSO was prepared and standardized as reported [14]. DMSO (Fluka; > 99%) was purified by distillation according to [14], degassed by a pumping-freezing procedure, and stored over 4 molecular sieves. Dien (Aldrich; > 97%) and dmdien, whose synthesis is described in [32] [33], were purified by fractional distillation [ 34] .…”

Section: Experimental Partmentioning

confidence: 99%

“…5 , respectively (see Table 6). [30], it was previously [14] assumed that this ion would be more strongly solvated by DMSO than by H 2 O on the basis of some comparisons between Zn 2 and Co 2 , characterized by similar charge density [31], and by the analysis of X-ray data of solvated derivatives [15b]. Therefore, the trend in the stability of the complexes in H 2 O and DMSO, unlike what might be expected on the basis of Co II solvation in the two solvents, is due to greater solvation of amines in H 2 O than in DMSO [24] complexes (L dien, dmdien) in DMSO is not rationalized only on the basis of the total basicity of the ligand as done previously, but seen as being mainly dependent on the structural features of the dioxygenated adduct.…”

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confidence: 99%

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Solvent Role on Cobalt(II) Dioxygen Carriers Based on Simple Polyamine Ligands

Piero

Ghezzi

Melchior

et al. 2005

Helvetica Chimica Acta

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The kinetics and thermodynamics of O 2 addition to Co II complexes containing the simple triamine ligand (L) diethylenetriamine ( N-(2-aminoethyl)ethane-1,2-diamine; dien) or N,N' '-dimethyldiethylenetriamine ( N-methyl-N'-[2-(methylamino) . The former, usually referred to as superoxo complexes, tend to be formed with sterically hindered ligands, in nonaqueous solvents, and at low temperatures, whereas in aqueous solutions, they are often only transient in the formation of the latter binuclear m-peroxo species. In fact, it is well-known that in aqueous solution, the formation of a mononuclear Co/O 2 1 : 1 adduct is immediately followed by a dimerization reaction leading to a binuclear mperoxo species in which O 2 bridges two metal ions [4]. The use of different solvent media in studying the same systems would therefore certainly provide a better understanding of the mechanisms involved in O 2 uptake.In addition, recent findings show that N-alkylation of some polyamine ligands strongly affects the redox properties of their metal complexes, since the oxidation tendency of the metal center is decreased when going from complexes of primary polyamines to complexes of tertiary ones [14 ± 19]. Their subsequent O 2 affinity is largely affected by the charge density on the metal center [1] and, therefore, by the s-

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supporting

confidence: 90%

Section: Experimental Partmentioning

confidence: 99%

Section: Experimental Partmentioning

confidence: 99%

mentioning

confidence: 99%

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Solvent Role on Cobalt(II) Dioxygen Carriers Based on Simple Polyamine Ligands

Piero

Ghezzi

Melchior

et al. 2005

Helvetica Chimica Acta

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“…In biology, Co(II) complexes are very important because they represent one of the most successful classes of synthetic oxygen carriers [13][14][15] . In this sense, the Co(II) complexes with N donor ligands are known for their ability to bind dioxygen more or less reversibly and therefore frequently studied for their importance in industrial processes and as model compounds [16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

The interaction between sulfathiazole and cobalt(II): potentiometric studies

Bellú¹,

Rizzotto²,

Okulik³

et al. 2007

Quím. Nova

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Recebido em 19/6/06; aceito em 17/11/06; publicado na web em 2/7/07Potentiometric studies of sulfathiazole (HST) in the presence and absence of cobalt(II) were performed. Equilibrium constants for the formation of the detected species, [Co(ST)] + and [Co(ST)(OH)], are reported. UV-Vis spectrophotometric measurements suggest that the coordination Co(II)-sulfathiazole might be through a N atom, which, in agreement with MO calculations, could be a thiazolic one. In spite of sulfonamides being better ligands at pH >7, [Co(ST)] + was found at pH ≈ 3.

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Cobalt(II) Complexes with Nitrogen Donors and Their Dioxygen Affinity in Dimethyl Sulfoxide

Comuzzi

Melchior

Polese

et al. 2002

Eur. J. Inorg. Chem.

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The formation of Co II complexes with differently methylated N-donor ligands ethylenediamine (en), N,NЈ-dimethylethylenediamine (dmen), N,N,NЈ-trimethylethylenediamine (trmen), and N,N,NЈ,NЈ-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.

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Thermodynamic studies on the complexation of cobalt(II) with nitrogen donor ligands in dimethyl sulfoxide

Cited by 17 publications

References 31 publications

Solvent Role on Cobalt(II) Dioxygen Carriers Based on Simple Polyamine Ligands

Solvent Role on Cobalt(II) Dioxygen Carriers Based on Simple Polyamine Ligands

The interaction between sulfathiazole and cobalt(II): potentiometric studies

Cobalt(II) Complexes with Nitrogen Donors and Their Dioxygen Affinity in Dimethyl Sulfoxide

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