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Determination of the stability constants for cobalt, nickel and palladium homogeneous catalyst complexes containing triphenylphosphine ligands

Paper ID Volume ID Publish Year Pages File Format Full-Text
44606 46044 2006 9 PDF Available
Title
Determination of the stability constants for cobalt, nickel and palladium homogeneous catalyst complexes containing triphenylphosphine ligands
Abstract

Homogeneous catalysts are complex compounds that are always in equilibrium with their free metal, free ligand and other forms of complexes. The ratios between different species are defined by the stability constants, which are influenced by different parameters such as the type of metal, ligand, counter ion or solvent. The main goal of this paper is the determination of the stability constants for a range of different homogeneous catalyst complexes and therefore the concentration of each species present in the solution. This information is needed for the modelling and design of reverse flow adsorption (RFA) technology, a novel concept for the recovery and recycling of homogeneous catalysts [J. Dunnewijk, H. Bosch, A.B. de Haan, Sep. Purif. Technol. 40 (3) (2004) 317–320; J. Dunnewijk, H. Bosch, A.B. de Haan, Adsorption 11 (2005) 521–526]. Cobalt, nickel and palladium halogens with triphenylphosphine as a ligand are selected as complexes since they are commonly used in homogeneous catalysis. Titration experiments with UV–vis spectroscopy as analytical technique have been carried out. The results were analyzed with a stability constant model developed for 1:2 complexation and adjusted for easy handling using Microsoft Excel. The stability constants of the selected complex systems increase in order: [PdCl2(OPPh3)2]acetonitrile ≈ [CoCl2(PPh3)2]butanol < [CoBr2(PPh3)2]acetonitrile < [CoCl2(PPh3)2]acetonitrile < [NiBr2(PPh3)2]acetonitrile < [PdCl2(PPh3)2]DMF < [PdCl2(PPh3)2]acetonitrile. The obtained results for the stability constants could be explained with the hard and soft acid base theory in combination with the natural order of different species theory.

Keywords
Reverse flow adsorption; Cobalt; Nickel; Palladium; Triphenylphosphine; Stability constants; 1:2 Complexation model
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Determination of the stability constants for cobalt, nickel and palladium homogeneous catalyst complexes containing triphenylphosphine ligands
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 312, 8 September 2006, Pages 144–152
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us