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EnglishCHIM03 Abstract: The coordination chemistry of the chiral bioxazoline ligand (4S,4'S)-2,2'-bis(4-isopropyl-4,5-dihydrooxazole) to Pd-II provides evidence that the ligand bonding can occur either through chelation of one Pd-II ion leading to a mononuclear species with the expected cis geometry, or by double bridging of two Pd-II ions giving a dinuclear complex with trans geometry. The species in solution are identified by H-1 NMR spectroscopy Both the mononuclear and the dinuclear complexes promote the CO/styrene copolymerization, yielding the corresponding polyketone with a fully or a predominantly isotactic microstructure, depending on the reaction medium. The nature of the anion present in the palladium precatalysts affects the polyketone stereochemistry. MALDI-TOF analysis of the copolymers synthesized reveals the presence of p-hydroxyphenolic end-groups, thus confirming and explaining the role of 1,4-hydroquinone as a molecular weight regulator.
| Titolo: | Mono- and dinuclear bioxazoline-palladium complexes for the stereocontrolled synthesis of CO/styrene polyketones | |
| Autori: | ||
| Data di pubblicazione: | 2005 | |
| Rivista: | ||
| Abstract: | CHIM03 Abstract: The coordination chemistry of the chiral bioxazoline ligand (4S,4'S)-2,2'-bis(4-isopropyl-4,5-dihydrooxazole) to Pd-II provides evidence that the ligand bonding can occur either through chelation of one Pd-II ion leading to a mononuclear species with the expected cis geometry, or by double bridging of two Pd-II ions giving a dinuclear complex with trans geometry. The species in solution are identified by H-1 NMR spectroscopy Both the mononuclear and the dinuclear complexes promote the CO/styrene copolymerization, yielding the corresponding polyketone with a fully or a predominantly isotactic microstructure, depending on the reaction medium. The nature of the anion present in the palladium precatalysts affects the polyketone stereochemistry. MALDI-TOF analysis of the copolymers synthesized reveals the presence of p-hydroxyphenolic end-groups, thus confirming and explaining the role of 1,4-hydroquinone as a molecular weight regulator. | |
| Handle: | http://hdl.handle.net/11368/1696426 | |
| Appare nelle tipologie: | 1.1 Articolo in Rivista |
