TY  - JOUR
UR  - https://doi.org/10.1016/S0277-5387%2800%2900453-8
SN  - 0277-5387
N2  - The stability constants and coordination modes of the mixed-ligand complexes formed by Cu(II), Ni(II), Zn(II), ethylenediamine
(en), 2,2%-bipyridine (bpy), glycinate (Gly), disodium salt of 4,5-dihydroxybenzene 1,3-disulfonate (Tiron), diethylenetriamine
(dien) or 2,2%:6,2¦-terpyridine (terpy) (ligand B) and acetohydroxamate (Aha), N-methylacetohydroxamate (MeAha) or
N-phenylacetohydroxamate (PhAha) (ligand A) were determined in water (25°C, I0.2 M KCl) by pH-metric, spectrophotometric,
EPR and calorimetric methods. Mixed-ligand complexes with typical hydroxamate type chelation mode involving the
NHO moiety are formed in all systems. However, further copper(II) induced deprotonation of the NHO moiety of Aha in the
presence of en or bpy results in the formation of mixed-ligand complexes with hydroximato chelates at high pH. The results show
the favoured coordination of a hydroxamate to metal(II)?en and especially to a metal(II)?bpy moiety. If ligand B is Gly, the
increase of stability of the mixed-ligand complexes is as expected on statistical basis, whereas the formation of complexes involving
O,O-coordinated hydroxamate and O,O-coordinated Tiron is unfavoured. The tridentate coordination of dien or terpy results in
five-coordinated mixed-ligand copper(II) complexes in which, most probably, the hydroxamate moiety adopts an equatorial?axial
coordination mode. This quite unstable hydroxamate chelate can not hinder the hydrolysis of the complex above pH 8. Under
very basic conditions acetohydroximato moieties (CONO2) displace the rigid terpy ligand from the coordination sphere and
complexes, [Cu(AhaH1)2]2 involving hydroximato chelates are formed.
A1  -  Farkas Etelka
A1  -  Enyedy Éva Anna
A1  -  Micera Giovanni
A1  -  Garibba Eugenio
TI  - Coordination modes of hydroxamic acids in copper(II), nickel(II) and zinc(II) mixed-ligand complexes in aqueous solution
N1  - Institute of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, Hungary            
            Department of Chemistry, University of Sassari, I-07100 Sassari, Italy            
            Cited By :92            
            Export Date: 2 October 2023            
            CODEN: PLYHD            
            Correspondence Address: Farkas, E.; Institute of Inorganic, , H-4010 Debrecen, Hungary; email: efarkas@delfin.klte.hu            
            Chemicals/CAS: 2,2' bipyridine, 366-18-7; acetohydroxamic acid, 546-88-3; diethylenetriamine, 111-40-0; ethylenediamine, 107-15-3; tiron, 149-45-1, 149-46-2            
            Funding details: Hungarian Scientific Research Fund, OTKA, T023612            
            Funding text 1: E.F. is grateful for support from OTKA T023612 and EU COST D8.
SP  - 1727
ID  - publicatio34379
EP  - 1736
JF  - POLYHEDRON
Y1  - 2000///
VL  - 19
AV  - public
IS  - 14
ER  -