Naslov
Kinetics and Mechanism of Iron(III)- Nitrilotriacetate Complex Reactions with Phosphate and Acetohydroxamic Acid

Autori
Gabričević, Mario ; Crumbliss, Alvin L.

Izvornik
Inorganic chemistry (0020-1669) 42 (2003), 13; 4098-4101

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
NTA ; Fe(III) ; Complexation ; Mechanism

Sažetak
The kinetics and mechanism of the substitution of coordinated water in nitrilotriacetate complexes of iron(III) (Fe(NTA)(OH2)2 and Fe(NTA)(OH2)(OH)-) by phosphate (H2PO4- and HPO42-) and acetohydroxamic acid (CH3C(O)N(OH)H) were investigated. The phosphate reactions were found to be pH dependent in the range of 4-8. Phosphate substitution rates are independent of the degree of phosphate protonation, and pH dependence is due to the difference in reactivity of Fe(NTA)(OH2)2 (k = 3.6 × 105 M-1 s-1) and Fe(NTA)(OH2)(OH)- (k = 2.4 × 104 M-1 s-1). Substitution by acetohydroxamic acid is insensitive to pH in the range of 4-5.2, and Fe(NTA)(OH2)2 and Fe(NTA)(OH2)(OH)- react at equivalent rates (k = 4.2 × 104 and 3.8 × 104 M-1 s-1, respectively). Evidence for acid- dependent and acid-independent back-reactions was obtained for both the phosphate and acetohydroxamate complexes. Reactivity patterns were analyzed in the context of NTA labilization of coordinated water, and outer- sphere electrostatic and H-bonding influences were analyzed in the precursor complex (Kos).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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