Document Detail

An (17)O-NMR Study of the Exchange of Water on AlOH(H(2)O)(5)(2+)(aq).
MedLine Citation:
PMID:  11670638     Owner:  NLM     Status:  Publisher    
The pH-dependence of the rate of water exchange between hydrated aluminum complexes and bulk aqueous solution is reported from variable-temperature dynamic (17)O-NMR measurements. Over the temperature range 298-348 K, the pseudo-first-order rate coefficient for exchange at any given temperature, is described by = + [H(+)](-1), where is the rate coefficient for exchange of inner-sphere water molecules with bulk solution for the Al(H(2)O)(6)(3+)(aq) complex at that temperature, and [H(+)](-1) is the pH-dependent contribution to from the first hydrolysis product: AlOH(H(2)O)(5)(2+)(aq). The rate parameters are = 1.3 s(-1), DeltaH(1)() = 84.7 kJ.mol(-1), DeltaS(1)() = 41.6 J.mol(-1).K(-1) (from 6); and = 7.2 x 10(-2) M.s(-1), DeltaH(2)() = 90.4 kJ.mol(-1), DeltaS(2)() = 36.6 J.mol(-1).K(-1) (this work). From this result we obtained the activation parameters for water exchange on the AlOH(H(2)O)(5)(2+)(aq) complex: = 3.1 x 10(4) s(-1), DeltaH() = 36.4 kJ.mol(-1), DeltaS() = -36.4 J.mol(-1).K(-1). Thus, deprotonation of an inner-sphere water in Al(H(2)O)(6)(3+)(aq) enhances by a factor of approximately 10(4) the lability of other inner-sphere oxygens. This labilizing effect of hydroxyl is much larger than for other geochemically important ligands, including fluoride.
Jan P. Nordin; David J. Sullivan; Brian L. Phillips; William H. Casey
Related Documents :
20095668 - Theoretical studies of absorption cross sections for the c (1)b(2)-x (1)a(1) system of ...
23999988 - Completing a family: licn3h4, the lightest alkali metal guanidinate.
17091948 - Atmospheric chemistry of n-c(x)f(2)(x)(+1)cho (x = 1, 2, 3, 4): fate of n-c(x)f(2)(x)(+...
16226808 - Uptake and metabolic effects of insulin mimetic oxovanadium compounds in human erythroc...
351178 - Checklist, host index, and annotated bibliography of plasmodium from reptiles.
21754788 - (1s,3s)-methyl 2-benzyl-6,7-dimeth-oxy-1-phenyl-1,2,3,4-tetra-hydro-isoquinoline-3-carb...
Publication Detail:
Journal Detail:
Title:  Inorganic chemistry     Volume:  37     ISSN:  1520-510X     ISO Abbreviation:  Inorg Chem     Publication Date:  1998 Sep 
Date Detail:
Created Date:  2001-Oct-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0366543     Medline TA:  Inorg Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  4760-4763     Citation Subset:  -    
Department of Land, Air and Water Resources; Chemical Engineering and Materials Science; and Department of Geology, University of California, Davis, California 95616.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Monocyclopentadienyl-Titanium Aryloxide Sulfide Complexes.
Next Document:  Low-Temperature Syntheses and Characterization of Novel Layered Tellurites, A(2)Mo(3)TeO(12) (A = NH...