Reversible, High Molecular Weight Palladium and Platinum Coordination Polymers Based on Phosphorus Ligands
摘要:
A general strategy for the preparation and characterization of high molecular weight coordination polymers based on bifunctional phosphorus ligands and palladium or platinum dichloride is described. Metal-to-ligand stoichiometry is of key importance for the formation of linear coordination polymers with high degrees of polymerization and was studied in detail. Heating of precursor complexes in the melt led to the highest degrees of polymerization. Peak molecular weights of 71000 g/mol were reached, corresponding to a degree of polymerization of 100 units. The coordination polymers based on palladium dichloride were demonstrated to be linear by performing a stopper experiment. Complexation with platinum resulted in the formation of a network polymer due to platinum's ability to coordinate three phosphorus atoms. The palladium coordination polymers form reversibly and are in equilibrium with rings. The concentration dependence of the ring-chain equilibria was studied for the palladium complexes with P-31 NMR and size exclusion chromatography, and critical concentrations of 70-180 mM were determined, below which no polymers are present.
Reversible Switching of the Sol−Gel Transition with Ultrasound in Rhodium(I) and Iridium(I) Coordination Networks
作者:Jos M. J. Paulusse、D. J. M. van Beek、Rint P. Sijbesma
DOI:10.1021/ja067523c
日期:2007.2.1
days at -20 degrees C. 31P NMR measurements on model complexes showed that the large differences in gelation times are in agreement with the ligand exchange kinetics of the rhodium(I) and iridium(I) complexes. We propose that sonication of the gels results in ligand exchange, which changes the network topology without changing the coordinationchemistry. Upon sonication, the fraction of metal centers in
Reversible, High Molecular Weight Palladium and Platinum Coordination Polymers Based on Phosphorus Ligands
作者:Jos M. J. Paulusse、Jeroen P. J. Huijbers、Rint P. Sijbesma
DOI:10.1021/ma050561g
日期:2005.7.26
A general strategy for the preparation and characterization of high molecular weight coordination polymers based on bifunctional phosphorus ligands and palladium or platinum dichloride is described. Metal-to-ligand stoichiometry is of key importance for the formation of linear coordination polymers with high degrees of polymerization and was studied in detail. Heating of precursor complexes in the melt led to the highest degrees of polymerization. Peak molecular weights of 71000 g/mol were reached, corresponding to a degree of polymerization of 100 units. The coordination polymers based on palladium dichloride were demonstrated to be linear by performing a stopper experiment. Complexation with platinum resulted in the formation of a network polymer due to platinum's ability to coordinate three phosphorus atoms. The palladium coordination polymers form reversibly and are in equilibrium with rings. The concentration dependence of the ring-chain equilibria was studied for the palladium complexes with P-31 NMR and size exclusion chromatography, and critical concentrations of 70-180 mM were determined, below which no polymers are present.
Maier,L., Angewandte Chemie, 1968, vol. 80, p. 401