Model Ziegler-Natta [alpha]-olefin polymerization catalysts derived from [([eta][sup 5]-C[sub 5]Me[sub 4]) SiMe[sub 2] ([eta][sup 1]-NCMe[sub 3])(PMe[sub 3])Sc([mu][sub 2]-H)][sub 2] and [([eta][sup 5]-C[sub 5]Me[sub 4] SiMe[sub 2]([eta][sup 1]-NCMe[sub 3])) Sc([mu][sub 2]CH[sub 2]CH[sub 2]CH[sub 3])][sub 2]. Synthesis, structures, and kinetic and equilibrium investigations of the catalytically active species in solution

Journal Article · Wed Jun 01 00:00:00 EDT 1994 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00090a011· OSTI ID:7069751

Shapiro, P J; Cotter, W D; Schaefer, W P; Labinger, J A; Bercaw, J E ^[1]

---

1. California Inst. of Technology, Pasadena, CA (United States)

The scandium hydride complex [(Cp*SiNR)(PMe[sub 3])Sc([mu]-H)][sub 2], (1) ((Cp*SiNR) = (([eta][sup 5]-C[sub 5]Me[sub 4])SiMe[sub 2]([eta][sup 1]-NCMe[sub 3]))) is prepared by hydrogenation of (Cp*SiNR)ScCH(SiMe[sub 3])[sub 2] in the presence of trimethylphosphine. The hydride complex is a catalyst precursor for the polymerization of [alpha]-olefins, yielding atactic products of low molecular weight (M[sub n] = 3000-7000). GC/MS analysis of volatile, oligomeric products revealed that all scandium centers are active during the polymerization. Selectivity for head-to-tail insertion is high (> 99%) and for the tetramer, pentamer, and hexamer formed during propene polymerization, the maximum theoretical numbers of head-to-tail stereoisomers are observed by capillary GC. The stoichiometric reaction between 1 and 2 equiv of ethylene produces the unusual ethylene-bridged dimer [(Cp*SiNR)(PMe[sub 3])Sc][sub 2]([mu], [eta][sup 2]-C[sub 2]H[sub 4]) (2) and an equivalent of ethane, whereas the same reaction with propene affords the phosphine-free, alkyl-bridged scandium dimer [(Cp*SiNR)Sc][sub 2]([mu]-CH[sub 2]CH[sub 2]CH[sub 3])[sub 2] (3). The absence of coordinating phosphine allows the latter complex to function as a more active olefin polymerization catalyst precursor. 1 reacts with styrene to form a unique double-insertion product arising from sequential 1,2- and 2,1-styrene insertion. 41 refs., 13 figs., 9 tabs.

• OSTI ID: 7069751
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 116:11; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKENES
POLYMERIZATION
SCANDIUM COMPLEXES
MOLECULAR STRUCTURE
SYNTHESIS
ZIEGLER CATALYST
EQUILIBRIUM
ETHYLENE
EXPERIMENTAL DATA
GAS CHROMATOGRAPHY
HYDRIDES
HYDROGENATION
MASS SPECTROSCOPY
NUCLEAR MAGNETIC RESONANCE
PHOSPHINES
SILICON COMPOUNDS
THEORETICAL DATA
X-RAY DIFFRACTION
CATALYSTS
CHEMICAL REACTIONS
CHROMATOGRAPHY
COHERENT SCATTERING
COMPLEXES
DATA
DIFFRACTION
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOSPHORUS COMPOUNDS
RESONANCE
SCATTERING
SEPARATION PROCESSES
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures