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Influence électronique et stérique du ligand tétraméthylcyclopentadiényle sur les propriétés physiques et sur la réactivité de complexes du titane et du zirconium
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1991
Year
Materials ScienceInorganic ChemistryChemical EngineeringC 5Specific Isomerization ReactionsEngineeringNatural SciencesCoordination ComplexPhysical ChemistryMolecular ComplexCatalysisChemistryQuantum ChemistryDu ZirconiumMr 1Inorganic SynthesisInorganic Compound
The complexes (C 5 Me 4 H) 2 MR 1 R 2 (M = Ti, Zr) and (C 5 Me 4 H)(C 5 H 5 )MR 1 R 2 (M = Ti) have been prepared (R 1 = R 2 = Cl, CH 3 , C 6 H 5 , p-C 6 H 4 CH 3 , CO; R 1 = Cl, R 2 = CH 3 , C 6 H 5 , p-C 6 H 4 CH 3 ). The NMR and IR spectra of these complexes indicate that C 5 Me 4 H exhibits an electron-donor effect more important than C 5 H 5 and a little bit weaker than that of C 5 Me 5 . A structural investigation of the complex (C 5 Me 4 H) 2 Zr(C 6 H 5 )Cl and the study of the 1 H or 13 C dynamic NMR properties of the compounds (C 5 Me 4 H) 2 MR 1 R 2 (M = Ti, Zr; R 1 = R 2 = C 6 H 5 , p-C 6 H 4 CH 3 ; R 1 = Cl, Br, R 2 = C 6 H 5 , p-C 6 H 4 CH 3 ) show clearly that C 5 Me 4 H has a steric effect intermediate between C 5 H 5 and C 5 Me 5 . The steric or electronic effects of C 5 Me 4 H have been used to induce specific isomerization reactions of various alkenes by using (C 5 Me 4 H) 2 Ti(CH 3 ) 2 as catalyst. Key words: zirconium, titanium, tetramethylcyclopentadienyl, photo-assisted, isomerization.