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Kinetics and Mechanism of Ligand Substitution in Some Chromium(III) Tetraaza Macrocyclic Complexes in Acidic Media: Differences in Reactivity Between cis and trans Isomers
Author(s) -
Madej Edyta,
Katafias Anna,
Kita Przemysław,
Eriksen Jette,
Mønsted Ole
Publication year - 2006
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200600627
Subject(s) - chemistry , aquation , reactivity (psychology) , thiocyanate , chromium , medicinal chemistry , kinetics , ligand (biochemistry) , macrocyclic ligand , substitution reaction , stereochemistry , reaction rate constant , inorganic chemistry , crystallography , organic chemistry , crystal structure , medicine , biochemistry , physics , alternative medicine , receptor , pathology , quantum mechanics
Thiocyanate anation of the macrocyclic complexes cis ‐[Cr(cyc b )(OH 2 ) 2 ] 3+ and trans ‐[Cr(cyc a )(OH 2 ) 2 ] 3+ (cyc b and cyc a are rac ‐ and meso ‐5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane, respectively), and mercury(II)‐induced aquation of the product thiocyanato‐ N complexes, has been studied in acidic solution. The rate retardation with an increase of the acid concentration for both types of reactions follows the rate expression k obs = ( k 1 + k 2 K a /[H + (aq) ])/(1 + K a /[H + (aq) ]), corresponding to parallel reaction paths through aqua and hydroxo complexes. Some general trends in the differences in reactivity between the two geometrical isomers have been observed and are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)