Monocomplex formation and dissociation of some first row divalent transition metal ions with 2-chloro-1,10-phenanthroline by the high-pressure stopped-flow technique
✍ Scribed by Gábor Laurenczy; Pascal Bugnon; André E. Merbach
- Book ID
- 104138760
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 860 KB
- Volume
- 198-200
- Category
- Article
- ISSN
- 0020-1693
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✦ Synopsis
The kinetics of the monocomplex formation and dissociation of [Co(Cl-phen)]" and [Ni(Cl-phen)]" (Cl-phen = 2chloro-l,lO-phenanthroline) in aqueous solution have been studied as a function of temperature, pressure and excess metal ion. The dissociation of these complexes was followed by adding Cu2+ to a solution of the complex [Co(Cl-phen)]" or [Ni(Cl-phen)]". The rate constants, activation enthalpies, entropies and volumes, and the corresponding thermodynamic parameters obtained for [Co(Cl-phen)]'+ (and for [Ni(Cl-phen)]'+) are as follows: e's (M-' s-')=5.7x104 (1.3x103); eg8 (s-')=7.1 (0.025); AH: (kJ mol-') =47.1 (53.5); AH: (kJ mol-') =59.2 (80.7); A# (J K-' mol-')= +4 (-6); ASf (J K-' mol-')= -30 (-5); AVj (cm' mol-')= +6.6 (+6.0); Avf (cm' mole')= +0.2 (+2.1); log Kzg8 (M-')=3.91 (4.71); AH" (kJ mol-')= -12.1 (-27.2);
AS" (J K-' mol') = + 34 ( -1); A v" (cm" mol-') = + 6.4 (+ 3.9). It is concluded that the complex formation reactions on both metal ions take place via dissociative interchange Id mechanisms.