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Kinetics of the Base‐Catalysed Isomerization of trans‐meso‐CH 3 Co(H 2 O)L 2+ (L = 5,7,7,12,14,14‐Hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,11‐diene)
Author(s) -
Lee Shaoyung,
Hung ChiaHsi
Publication year - 1998
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199800112
Subject(s) - chemistry , isomerization , kinetics , aqueous solution , medicinal chemistry , base (topology) , reaction rate constant , stereochemistry , reaction mechanism , catalysis , organic chemistry , mathematical analysis , physics , mathematics , quantum mechanics
The isomerization of the complex trans‐meso‐CH 3 Co(H 2 O)L 2+ (L = 5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,11‐diene) to trans‐primary, rac‐CH 3 Co(H 2 O)L 2+ has been investigated from pH range 7.11 to 8.09 in aqueous solution. The reaction rate law has been determined as: ‐d[meso‐CH 3 Co(H 2 O)L 2+ ]/dt = k OH [OH − ][meso‐CH 3 Co(H 2 O)L 2+ ], where k OH = 600 ± 10 M −1 s −1 at 25 °C and μ = 0.5 M. The activation parameters of the reaction were also studied with ΔH ± = 19.1 ± 0.9 Kcal mol −1 and ΔS ± = 18.0 ± 0.8 cal K −1 mol −1 . A mechanism that involves a secondary NH inversion is proposed.