Complexes of the Trivalent Rare Earths with Isobutyrate, α-Hydroxyisobutyrate, and α,β,β'-Trihydroxyisobutyrate Ligands

Stagg, William Ray; Powell, J.E.

doi:10.1021/ic50012a023

Cited by 45 publications

(14 citation statements)

References 2 publications

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“…POWELL and co-workers [8][9][10][11] in the studies with tripositive lanthanons and a,/?-substituted, mono and dihydroxy carboxyhc acids, have established that, the gadolinium break and a rather abrupt decline in Ki/K2 ratios, as the lanthanon radii decreases beyond that of Sm 3+ , is an indication of a change from tridentate to bidentate hgancy, combining with a nine cdordinate (tricapped trigonal prism) hydrated lanthanon. They have cited BJEKRUMS theory 12 , that ratios of successive step formation constants depend principally upon individual formation and decomposition statistics relating to ABRA_I and AB" chelate species; BJEK-RUMS theory can be in general expressed as: P* = *Kn-i/*Kn = SRT, at ionic strength other than zero: P = K"^/Kn = (*Kn-x/*Kn) {u) = SRT f (u) where P* is the ratio of true thermodynamic step formation constant (at infinite dilution), S is the purely statistical consideration, T is the electrostatic factor, R is a general rest factor (including hgand assymmetry and steric effect).…”

Section: Discussionmentioning

confidence: 99%

Potentiometric Determination of Stability Constants of Trivalent Metal Ion Complexes with Di-p-tolyl-thiovioluric Acid

Mathur

Goel

Singh

1976

Zeitschrift Für Naturforschung B

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Potentiometrie Determination, Stability Constants, Di-p-tolyl-thiovioluric AcidThe consecutive formation constants of 1:1, 2:1, 3:1 chelate species formed by the interaction of di-p-tolyl-thiovioluric acid (D-p-TOTVA) with the tripositive lanthanons and yttrium cations were determined potentiometrically at 0.1 /i (NaC104) at 30 i 1 °C, in 75% aqueous dioxan.The 1:1 formation constants (log A'i) for the complexes increase with the increase in the atomic number of the lanthanon (3), with a break at gadolinium.The results indicate that the ligand bonds bidentately to heavier lanthanons (smaller ionic radii). However, definite dentate character of bonding to lighter (larger ionic radii) lanthanons could not be established.

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Section: Discussionmentioning

confidence: 99%

Potentiometric Determination of Stability Constants of Trivalent Metal Ion Complexes with Di-p-tolyl-thiovioluric Acid

Mathur

Goel

Singh

1976

Zeitschrift Für Naturforschung B

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“…The experimental results show that P is smaller for the smaller rare-earth ions and that there is no trend within the two different series of P values. Clearly, electrostatic repulsion is of secondary importance in Data of Sonesson (15). A Data of Fronaeus (7).…”

Section: Table Imentioning

confidence: 99%

Rare-Earth Acetate Ion Association

Manning¹

1965

Can. J. Chem.

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Furthermore, all values of pKE1,= lie too negative to admit of any significant amount of I-12L2f being formed during pH titrations suitable for determination of stability constants of metal conlplexes. Therefore, the existence of protonated metal complexes is possibly indicated, and is being investigated by the author. The correlation between p 1 k L and pKE12L is not conlpletely satisfactory, but the two sets of values clearly follolv the same trend. EXPERIMENTAL The phenanthrolines were purchased from the G. F. Smith Chemical Company, the bipyridyl from British Drug I-louses, and were all subjected to purification as follows: First, they were recrystallized from warm benzene, then dissolved in dilute hydrochloric acid, and re-precipitated by the addition of s o d i~~m hydroxide. This process was repeated, if necessary, until the product obtained melted sharply and a t the ~nelting point published for the appropriate compound. Solutio~~s of these compounds were prepared in hydrochloric or perchloric acid of known molarity prepared by the addition of measured volun~es of a concentrated analyzed stock acid to a fixed final volume. The perchlorates of these bases are rather insoluble, so that only 1,lO-phenanthroline could be measured over a wide range of perchloric acid concentrations. Absorption spectra were measured with a Cary Model 14 spectrophotometer. I n some cases, optical densities at single wavelengths were measured in a Beckman Model DU spectrophotometer.

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“…Setting expression 10 equal to expression 11, one, obtains ,r$2 least squares treatment~used is patterned after that of ~~~of Rydberg (11), and Sullivan, Rydgerg and Miller (12), ~~ The mathematical co~putations were written in a computer program.by Stagg (13). Equation 12 is not in ~·general equal to zero for each data point, but, rather, one obtains a residual ui as indicated in equation …”

Section: ---_ __ 'T/1/-~_ "---------T /~ ~- --~~ ----~----mentioning

confidence: 99%

Stabilities of some rare-earth malonato chelate species in aqueous and methyl alcohol solution

Johnson

1971

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Complexes of the Trivalent Rare Earths with Isobutyrate, α-Hydroxyisobutyrate, and α,β,β'-Trihydroxyisobutyrate Ligands

Cited by 45 publications

References 2 publications

Potentiometric Determination of Stability Constants of Trivalent Metal Ion Complexes with Di-p-tolyl-thiovioluric Acid

Potentiometric Determination of Stability Constants of Trivalent Metal Ion Complexes with Di-p-tolyl-thiovioluric Acid

Rare-Earth Acetate Ion Association

Stabilities of some rare-earth malonato chelate species in aqueous and methyl alcohol solution

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