EQUILIBRIUM CONSTANTS FOR THE FORMATION OF POLYNUCLEAR TRIDENTATE 1:1 CHELATES IN URANYL-MALATE,-CITRATE, AND -TARTRATE SYSTEMS. DEFORMATION OF THE URANYL ENTITY
pH titrations were analyzed to determine the over-all dimerization constants, K/sub III/, and the trimerization constants, K/sub Tr/, for the tridentate 1: 1 chelates in the uranylmalate, -citrate, and -d-tartrate systems at 25 deg C. For these three systems, respectively, log/sub 10/K/sub III/ was found to be 0.20, pK/sub Tr/, was 10.56 plus or minus 0.05 for the uranyl- malate system and 9.7 plus or minus 0.12 for the uranyl-d-tartrate system. The unexpected increase in the tendency of uranium to polymerize after tridentate chelation is explained on the basis of decreased 5f orbital participation in the uranium to oxygen bonds of the uranyl entity as a result of deformation of the normally-collinear uranyl entity. The fact that relative to the uranyl-malate system the uranyl-d-tartrate system has a lower K/sub III/ but higher K/sub Tr/ is believed due to more hydrogen bonding plus greater inductive effect in the tartrate ion than in malate ion. In accord with these hypotheses, the equimolar uranyl-meso-tartrate system seems to contain a mixture of unhydrolyzed mononuclear bidentate chelate and olated binuclear tridentate chelate. (auth)
- Research Organization:
- Rochester, N.Y. Univ. Atomic Energy Project
- NSA Number:
- NSA-14-017797
- OSTI ID:
- 4178704
- Report Number(s):
- UR-559
- Country of Publication:
- United States
- Language:
- English
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