Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol.
A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.
Department of Chemistry, Faculty of Pharmacy, Medical University, Sofia 1000, Bulgaria. irenakostova@yahoo.com
Irena
I
Kostova
Ilia
I
Manolov
Maritza
M
Radulova
D000074:Acenocoumarol / Q000032:analysis / Q000737:chemistry*; D003374:Coumarins / Q000032:analysis / Q000737:chemistry; D004355:Drug Stability; D028581:Lanthanoid Series Elements / Q000032:analysis / Q000737:chemistry*; D009354:Neodymium / Q000032:analysis / Q000737:chemistry*
D003374:Coumarins; D028581:Lanthanoid Series Elements; D009354:Neodymium; C030123:coumarin; D000074:Acenocoumarol