Titanium ferrocenyl-phosphinimide complexes.
Oxidation of [CpFe(eta(5)-C(5)H(4)PtBu(2))] with Me(3)SiN(3) gave the phosphinimine [CpFe(eta(5)-C(5)H(4)PtBu(2)NSiMe(3))] (1) which was used to prepare [Cp'TiCl(2)(NPtBu(2)C(5)H(4))FeCp] (Cp' = Cp , Cp* 4) and subsequently [Cp'TiMe(2)(NPtBu(2)C(5)H(4))FeCp] (Cp' = Cp 3, Cp* 5). Similarly, [(eta(5)-C(5)Ph(5))Fe(eta(5)-C(5)H(4)PtBu(2)NSiMe(3))] 6 was converted to [CpTiX(2)(NPtBu(2)C(5)H(4))Fe(eta(5)-C(5)Ph(5))] (X = Cl 7, Me 8). The bis-phosphinimine [Fe{eta(5)-C(5)H(4)PtBu(2)(NSiMe(3))}(2)] (9) was prepared and used to obtain [{Fe(eta(5)-C(5)H(4)PtBu(2)N)(2)}TiCl(2)] (10) and [{Fe(eta(5)-C(5)H(4)PtBu(2)N)(2)}TiMe(2)] (11). These species exhibited a temperature dependent conformational change in the chelate geometry on the NMR time scale. Cyclic voltammetry studies showed pseudo reversible redox waves assigned to the Fe(2+)/Fe(3+) couple for 2 and 4, while 10 exhibited only irreversible oxidations. Compound was also used to prepare [Fe(eta(5)-C(5)H(4)PtBu(2)NTiXCl(2))(2)] (X = Cl 12, Cp 13, Cp* 15). Compounds 3 and 5 react with B(C(6)F(5))(3) or [CPh(3)][B(C(6)F(5))(3)] to generate salts of the formula [Cp'TiMe{(NPtBu(2)C(5)H(4))FeCp}]X (Cp' = Cp, X = [MeB(C(6)F(5))(3)] 17a, [B(C(6)F(5))(4)] 17b; Cp' = Cp*, X = [MeB(C(6)F(5))(3)] 18a, [B(C(6)F(5))(4)] 18b). Compounds 18 further generated [Cp*TiMe{HNPtBu(2)(C(5)H(4))Fe(eta(5),eta(1)-C(5)H(4))}]X (X = [MeB(C(6)F(5))(3)] 19a, [B(C(6)F(5))(4)] 19b), respectively. The cationic species 17a and 18a are very active polymerization catalysts, giving polyethylene with activities of 2400 and 5000 g mmol(-1) h(-1) atm(-1), respectively at 25 degrees C.
Ramos
Alberto
A
Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario, CanadaM5S 3H6.
Stephan
Douglas W
DW