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Metal Complexes with Macrocyclic Ligands. XIV. Formation, dissociation and metal exchange with an N 2 S 2 ‐macrocycle
Author(s) -
Kallianou Chariklia S.,
Kaden Thomas A.
Publication year - 1979
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19790620809
Subject(s) - chemistry , dissociation (chemistry) , metal , ligand (biochemistry) , kinetics , reactivity (psychology) , reaction rate constant , macrocyclic ligand , medicinal chemistry , ammonium , inorganic chemistry , crystallography , polymer chemistry , stereochemistry , organic chemistry , receptor , medicine , biochemistry , physics , alternative medicine , pathology , quantum mechanics
10, 10, 12‐Trimethyl‐3,4‐benzo‐1,6‐dithia‐9,13‐diazacyclopentadecen‐dihydrochloride (LH 2 2+ , 2 ) and its Ni 2+ complex were synthesized and their reactivity studied. The formation kinetics of 2 with Cu 2+ were found to be a second order reaction between Cu 2+ or CuACO + and the monoprotonated form of the ligand LH + . The rate constant k Cu LH= 29 M −1 S −1 is 10 5 –10 6 times smaller than those of monoprotonated tetraazamacrocycles either because of second bond formation or because of a strong electrostatic interaction between the positive charges of the Cu 2+ and the ammonium group. The metal‐metal exchange between NiL + and Cu 2+ was also investigated. The reaction is independent of [Cu 2+ ] and has the same rate and activation parameters as the dissociation of NiL 2+ . In contrast to open chain ligands, no mixed complex CuNiL 4+ as intermediate was observed.