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Titolo:
INTERNALLY PHOSPHINE-STABILIZED ZIRCONOCENE CATIONS EMPLOYING SUBSTITUTED ((DIARYLPHOSPHINO)METHYL) CYCLOPENTADIENYL LIGAND SYSTEMS
Autore:
BOSCH BE; ERKER G; FROHLICH R; MEYER O;
Indirizzi:
UNIV MUNSTER,INST ORGAN CHEM,CORRENSSTR 40 D-48149 MUNSTER GERMANY UNIV MUNSTER,INST ORGAN CHEM D-48149 MUNSTER GERMANY
Titolo Testata:
Organometallics
fascicolo: 25, volume: 16, anno: 1997,
pagine: 5449 - 5456
SICI:
0276-7333(1997)16:25<5449:IPZCES>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
STEREOSELECTIVE PROPENE POLYMERIZATION; ZIRCONIUM-MEDIATED FUNCTIONALIZATION; PHOSPHORUS CHELATE COMPLEXES; ZIEGLER-CATALYST PRECURSORS; C-H BONDS; OLEFIN POLYMERIZATION; INSERTION REACTIONS; ORGANOMETALLIC COMPOUNDS; RING CONTRIBUTIONS; CRYSTAL-STRUCTURE;
Tipo documento:
Review
Natura:
Periodico
Citazioni:
101
Recensione:
Indirizzi per estratti:
Citazione:
B.E. Bosch et al., "INTERNALLY PHOSPHINE-STABILIZED ZIRCONOCENE CATIONS EMPLOYING SUBSTITUTED ((DIARYLPHOSPHINO)METHYL) CYCLOPENTADIENYL LIGAND SYSTEMS", Organometallics, 16(25), 1997, pp. 5449-5456

Abstract

The dimethylzirconocene complex [(Cp-CMe2-PAr2)(2)ZrMe2], 2a (Ar = p-tolyl), was treated with 1 molar equiv of B(C6F5)(3) to yield the salt[(Cp-CMe2-PAr2)(2)ZrMe+MeB(C6F5)(3)(-)], 3a. The X-ray crystal structure analysis of 3a shows that both -PAr2 units are intramolecularly coordinated to zirconium in a close to C-2-symmetric arrangement with the [Zr]-CH3 group placed in the central position in the bent metallocene sigma-ligand plane. Treatment of 2a with 2 equiv of B(C6F5)(3) generates the highly reactive dication system [(Cp-CMe2-PAr2)(2)Zr2+] (4 with two MeB(C6F5)(3-) anions). The highly electrophilic cation 4 abstracts chloride from, e.g., dichloromethane solvent to yield [(Cp-CMe2-PAr2)(2)Zr-Cl+] (5, with MeB(C6F5)(3)(-) anion). The same cation (5', with ClB(C6F5)(3)(-) anion) was obtained from the reaction of [(Cp-CMe2PAr2)(2)ZrCl2] (1a) with B(C6F5)(3). The C-2-symmetric, internally -PAr2-stabilized dication adds acetonitrile or 2,6-dimethylphenyl isocyanide to give the respective C-2-symmetric donor-ligand adducts in which the -PAr2 coordination to zirconium is retained. The complexes 3a (Delta G double dagger(enant) (300 K) = 14.0 +/- 0.5 kcal/mol) and 5 (Delta G double dagger(enant) (360 K) = 17.5 +/- 0.5 kcal/mol) show dynamicNMR spectra due to an intramolecular enantiomerization process proceeding with a rate-determining cleavage of the Zr-P linkages. Complex 5 was also characterized by an X-ray crystal structure analysis.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/12/20 alle ore 09:42:02