ISSN:
1434-1948
Keywords:
Ethylene polymerization
;
Group 5 metal complexes
;
Hydridotris(pyrazolyl)borates
;
Alkyne ligands
;
Migratory insertion
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Substituted hydridotris(pyrazolyl)borato (Tp′) niobium complexes of the type [Tp′NbMe2(PhC≡CMe)] polymerize ethylene (under 1 atm, at room temp. and in toluene) when treated with an equimolar amount of B(C6F5)3. A clear relationship is observed between the stereoelectronic nature of the complex and catalytic activity. This is discussed on the basis of electrochemical data for the dichloro complexes [Tp′NbCl2(PhC≡CMe)], and the rates of alkyl migration in [Tp′Nb(Cl)(R)(PhC≡CMe)] (R = CH2Me, CH2SiMe3). For a given electron density at the metal, the bulky TpMe2,4-Cl yields a catalyst which is more than 6 times as active as the unsubstituted Tp based catalyst.
Type of Medium:
Electronic Resource
