ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The stability constants of the Ni2+ and Co2+ complexes with 1,5-diazacyclooctane-N,N′-diacetic acid (H2DACODA) have been determined potentiometrically in 0.5M KNO3 at 25°. Only M(DACODA) and M(DACODA)OH- were observed.In addition the formation and dissociation kinetics of the pentacoordinate complexes M(DACODA) has been studied in aqueous solution using a stopped-flow technique. Formation follows the rate law vf = kf [M2+] [HDACODA-]/[H+], which can be interpreted as a bimolecular process either between M2+ and DACODA2- (kM,LML) or between MOH+ and HDACODA- (kMOH,HLML). The second order rate constants kM,LML are much higher than those expected from water exchange and can only be explained by a strong internal conjugate base effect. In the limiting case, however, this is equivalent to the second possible explanation, which assumes MOH+ and HDACODA- as reactive species. The dissociation rate is given by vd = (kML + kHML [H+]) · [M(DACODA)].
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19750580703
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