Premium
Kinetics and mechanism of the photochemical reaction of Octacyanomolybdate (IV) and Diethylenetriamine
Author(s) -
Ali S. I.,
Majid Kowsar,
Ansari A. M. A.,
Kumar Ashutosh
Publication year - 1999
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1999)31:2<89::aid-kin2>3.0.co;2-m
Subject(s) - chemistry , diethylenetriamine , quantum yield , reaction rate constant , ionic strength , ligand (biochemistry) , photochemistry , protonation , photodissociation , reaction mechanism , stoichiometry , reaction rate , yield (engineering) , rate equation , kinetics , catalysis , aqueous solution , organic chemistry , ion , biochemistry , physics , receptor , materials science , quantum mechanics , metallurgy , fluorescence
Photolysis of [Mo(CN) 8 ] 4− in the presence of diethylenetriamine (dien) leads to the complexation of ligand via hydrogen in the stoichiometry 2:1. The mechanism of the complexation was investigated by spectroscopy absorption and the rate constants and the quantum yield determined. Rate constants and quantum yields for the formation of the final products were found to depend on pH, ligand, and metal cyanide concentration. The values are a maximum at pH 7.4. At pH >7.4 the reverse reaction, generating octacyanomolybdate complex from the heptacyano species, is faster. At low pH, the ligand is protonated and less reactive; hence, the rate of reaction and quantum yield values decrease. The ionic strength does not affect the reaction rate, implying an associative mechanism for the photochemical reaction with dien, supported by the rate law. The observed rate law is:$$k_{\rm {obs.}}={k_{2}k_{4}{\rm I}_{a}{\rm{[OH^{-}]}}{\rm{[ dien]}} \over 1+ k_{2}{\rm [OH^{-}]}}$$ © 1999 John Wiley & Sons, Inc. J Chem Kinet 31: 89–93, 1999