ABSTRACT
In the present work, binary complexes of Copper(II), Cadmium(II) and Zinc(II) with metformin hydrochloridehave been studied potentiometrically. Stability constants of binary complex systems have been estimated by themethod proposed by Irving-Rossotti at 25ºC and 0.11M ionic strength (NaClO4) in aqueous solution. Theconditional formation constants of the complexes formed between ligand and metal were calculated according topH function. The maximum values of the conditional formation constants were found to be in accordance with themixed metal-ligand complex formation constants in a given pH region. In addition to these, the molar fractionswere calculated using the formation constants of the mixed metal-ligand complexes. As a result of theexperimental study, the values of stability constants of metal-ligand complexes at 25ºCare as noted below:logK1=8.45; logK2=8.30 for Zn(II)-Metformin hydrochloride; logK1=8.78 ; logK2=8.00 for Cu(II)-Metforminhydrochloride: logK1=8.18; logK2=7.36 for Cd(II) – Metformin hydrochloride.
ABSTRACT
Thermodynamic protonation constants of 5-aldehydosalicylic acid Schiff base with aniline and related compounds such as o-chloro aniline, o-nitro aniline, o-anisidine, o-toluidine and with 7-amino-4-methyl coumarin have been determined by Calvin-Bjerrum pH titration technique as used by Irving and Rosssotti. The solution stability constants of their complexes with bivalent metal ions Cu(II), Zn(II), Ni(II), Co(II), Cd(II) and Mg(II) with these ligands have been determined at four temperature in 50% water-ethanol mixture at an ionic strength of 0.1M (NaClO4). The order of solution stability constants was found to be Zn < Cu > Ni > Co = Cd > Mg which is in agreement with Irving – William’s order. The values of ΔGo, ΔHo, ΔSo have been calculated for the various complex equilibrium. The Copper chelates found to be more stable than Zn and Ni chelates due to difference in their configurations. Cu(II) forms square planar complex while Zn(II), Ni(II) form a tetrahedral or octahedral complex. The log K value for Zn chelate is found to be higher as compared to that of Ni chelate in case of above said all reagents used for investigation.
ABSTRACT
Thermodynamic protonation constants of 5-aldehydosalicylic acid-aniline Schiff base, [5ASAA], and o-, m-, p-Toluidine Schiff bases with 5-aldehydosalicylic acid have been determined by Calvin –Bjerrum pH titration technique as used by Irving and Rossotti. The thermodynamic formation constants of the chelates of Cu (II), Co (II), Ni (II), Zn (II), Cd (II) and Mg (II) with these four ligands have been determined at four different temperatures in 50% (v/v) water-ethanol mixture; the stabilities of complexes follow the Irving-William’s order.