Synthesis and characterization of several lanthanide complexes with ethyl α-ketocyclopentyl carboxylate

Kinetics of monochelation of aqueous chromium(III) by methyl 2-oxocyclopentanecarboxylate

“…The observed linear dependence between k obs and chromium concentration, which may be presented as in Eqn. (13), may be justified from the data in Table 1 This was verified in all cases with excellent correlation coefficients. The k 1 and k 2 values obtained from the slopes agree fairly well with those obtained from the overall fitting, as was expected.…”

“…9 This can be explained by the solvation of the carbonyl groups by the polar solvent molecules, which increases the stability of the keto forms, and this is found to be true in the case of methyl 2-oxocyclopentanecarboxylate. In fact, our analysis of the 1 H and 13 C NMR spectra indicated that the keto tautomer of methyl 2-oxocyclopentanecarboxylate (HMCP k ) was present in D 2 O-CD 3 OD aqueous solution at 25°C, while the enol tautomer (HMCP e ) was undetected, indicating less than 5% of enol form in the medium.…”

“…Comparative studies using Fourier transform IR and 13 C NMR spectroscopy concluded that methyl 2-oxocyclopentanecarboxylate exists solely in the keto 27 form in the pure liquid and in CDCl 3 solution phase. On the other hand, the enol forms are present in all phases in C 6 , C 7 and C 8 cycloalkane derivatives.…”

“…In fact, bketo esters behave as bidentate ligands, forming coordination compounds with metal ions such as Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and La(III), Ce(III) and Pr(III). 12,13 These complexes usually contain coordinated water molecules, thus completing a distorted octahedral coordination around the metallic site. The immediate environment of the metal in these complexes is very similar to that existing in their acetylacetonate compounds, e.g.…”

“…The standard cell length was 1 cm. 1 H and 13 C NMR spectra were recorded on Bruker AC-300 and ARX-300 instruments at 300 and 75 MHz, respectively, in D 2 O-CD 3 OD; chemical shifts are given in ppm relative to tetramethylsilane (TMS) as internal standard.…”