Ligand exchange reactions between copper(II)- and nickel(II)-chelates of different sulfur- and selenium-containing ligands. VI [1]. Kinetics of ligands exchange reactions studied by stopped-flow ESR
✍ Scribed by J. Stach; R. Kirmse; W. Dietzsch; G. Lassmann; V.K. Belyaeva; I.N. Marov
- Publisher
- Elsevier Science
- Year
- 1985
- Tongue
- English
- Weight
- 417 KB
- Volume
- 96
- Category
- Article
- ISSN
- 0020-1693
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✦ Synopsis
enolates) were found to have an equilibrium constant ofK=4. The kinetics of ligand exchange reactions studied by means of stopped-flow ESR measurements are reported. The concentration-time curves recorded for all reactions investigated correspond to simple second-order rate laws. The rate constants of the reactions between copper(I1) dithiolenes and Cu(Etzdsc)2 (Et2dsc = diethyldiselenocarbamate) or Ni(Etzdsc)2 were found to be: [Cu(mnt),] '-(mnt = maleonitriledithiolate) + Cu(EtZdsc)Z, kz = (2.3 + 0.3). IO* 1 mol-' s-'; [Cu(mnt),]'-+ Ni(Et,dsc)*, k2 = (2.1 + O.l)*lO* 1 mol-' s-' and [Cu(dmit)2]2-(dmit = isotrithione3.4-dithiolate) + Ni(Et*dsc)*, k2 = (2.5 f 0.3). lo* 1 mol-' s-l. A rate constant of k2 = (2.0 f 0.3)*10* 1 mol-' s-' was determined for the reaction between Cu(Et2dsc)2 and Cu(Et,dtc),(Et,dtc = diethyldithiocarbamate).
(III) Reactions between complexes containing strongly different ligands could not be classified as unitary.
This classification is also true if the reactions take place between corresponding Ni(I1) and Pd(I1) chelates.
Additional experiments suggest a chain mechanism for the ligand exchange reactions in which the monochelates e.g. [Cu(mnt)], react as active sites.