The system formed by Cu(II) and 2,2'-bipyridine (bpy) has been revisited by use of EPR and electronic absorption spectroscopies. The mono-chelated [Cu(bpy)](2+), bis-chelated trans-[Cu(bpy)(2)](2+) with pseudo-tetrahedral geometry due to the steric hindrance of the 3,3' hydrogen atoms and tris-chelated [Cu(bpy)(3)](2+) species exist in aqueous solution. In basic media hydrolysis yields [Cu(bpy)OH](+) and [Cu(bpy)(OH)(2)]. The dimer [Cu(bpy)(OH)](2)(2+) is favoured by increasing metal ion concentration in the pH range 8-10. The EPR spectrum of the dimeric species shows well-resolved Delta M = 1 and 2 features, and is different from that observed in the solid state. The zero-field splitting is consistent with a distance of similar to 3.4 Angstrom between metallic centres. The behaviour of the complex system is in agreement with potentiometric data reported in the literature. In the EtOH-H2O mixture the bis-chelated complex adopts a five-coordinate cis structure exhibiting a rhombic EPR spectrum and, in basic solution, the [Cu(bpy)(2)(OH)](+) species is formed. The attribution of the solution species has been confirmed by the analysis of solid compounds, [Cu(bpy)SO4]. 2H(2)O, [Cu(bpy)(H2O)(2)](NO3)(2) [Cu(bpy)(2)OSO3]. 4H(2)O and [Cu(bpy)(2)ONO2]NO3. H2O, after dissolution. (C) 2000 Elsevier Science S.A. All rights reserved.

The Cu(II)-2,2 '-bipyridine system revisited / Garribba, Eugenio; Micera, Giovanni; Sanna, D; Strinna Erre, L.. - In: INORGANICA CHIMICA ACTA. - ISSN 0020-1693. - 299:2(2000), pp. 253-261. [10.1016/S0020-1693(99)00508-3]

The Cu(II)-2,2 '-bipyridine system revisited

GARRIBBA, Eugenio;MICERA, Giovanni
;
2000

Abstract

The system formed by Cu(II) and 2,2'-bipyridine (bpy) has been revisited by use of EPR and electronic absorption spectroscopies. The mono-chelated [Cu(bpy)](2+), bis-chelated trans-[Cu(bpy)(2)](2+) with pseudo-tetrahedral geometry due to the steric hindrance of the 3,3' hydrogen atoms and tris-chelated [Cu(bpy)(3)](2+) species exist in aqueous solution. In basic media hydrolysis yields [Cu(bpy)OH](+) and [Cu(bpy)(OH)(2)]. The dimer [Cu(bpy)(OH)](2)(2+) is favoured by increasing metal ion concentration in the pH range 8-10. The EPR spectrum of the dimeric species shows well-resolved Delta M = 1 and 2 features, and is different from that observed in the solid state. The zero-field splitting is consistent with a distance of similar to 3.4 Angstrom between metallic centres. The behaviour of the complex system is in agreement with potentiometric data reported in the literature. In the EtOH-H2O mixture the bis-chelated complex adopts a five-coordinate cis structure exhibiting a rhombic EPR spectrum and, in basic solution, the [Cu(bpy)(2)(OH)](+) species is formed. The attribution of the solution species has been confirmed by the analysis of solid compounds, [Cu(bpy)SO4]. 2H(2)O, [Cu(bpy)(H2O)(2)](NO3)(2) [Cu(bpy)(2)OSO3]. 4H(2)O and [Cu(bpy)(2)ONO2]NO3. H2O, after dissolution. (C) 2000 Elsevier Science S.A. All rights reserved.
The Cu(II)-2,2 '-bipyridine system revisited / Garribba, Eugenio; Micera, Giovanni; Sanna, D; Strinna Erre, L.. - In: INORGANICA CHIMICA ACTA. - ISSN 0020-1693. - 299:2(2000), pp. 253-261. [10.1016/S0020-1693(99)00508-3]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/83562
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