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Mechanism of nucleophilic substitution in chromium(III) complexes. III. formation of Azidopentamminechromium(III) ion from aquopentamminechromium(III) ion in NaN 3 –HN 3 buffer media
Author(s) -
Banerjea D.,
Sarkar S.
Publication year - 1972
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.19723930314
Subject(s) - chemistry , chromium , kinetics , medicinal chemistry , conjugate , ion , azide , reaction mechanism , reaction rate constant , inorganic chemistry , base (topology) , substitution reaction , nucleophile , catalysis , organic chemistry , mathematical analysis , physics , mathematics , quantum mechanics
The kinetics of formation of [Cr(NH 3 ) 5 N 3 ] 2+ in the reaction of [Cr(NH 3 ) 5 (OH 2 ) 3+ ] in NaN 3 –HN 3 buffer media (pH ca. 3.4–4.3) has been studied spectrophotometrically under different conditions for elucidation of reaction mechanism. The reaction occurs in two concurrent paths involving reactions of the aquo complex and its conjugate base (the hydroxo complex) with azide ion (gross rate constants k 1 and k 2 respectively). Results, including values of the activation parameters (ΔH≠ and ΔS≠) are in agreement with S N 1 IP mechanism for both the paths. The observed relativ nucleophilicityo of N 3 − compared to that reported in literature for Cl − and NCS − is N 3 −> NCS − > Cl − .