Jenny S J McCahill

University of Windsor, Windsor, Ontario, Canada

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Publications (6)24.8 Total impact

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    ABSTRACT: Frustrated Lewis pairs (FLPs) derived from R3P (R = otol, Mes) and B(C6F5)3 or AlX3 (X = halide, C6F5) add to ethylene. Similarly, the P/B FLP adds across propylene, whereas the P/Al systems react with propylene to effect propylene dimerization via a C–H bond activation and C–C bond formation, affording an Al-bound 2-methylpentene complex.
    Organometallics 04/2013; 32(22):6759–6763. · 4.25 Impact Factor
  • Jenny S.J. McCahill, Douglas W. Stephan
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    ABSTRACT: The copolymerization of 1-hexene with t-Bu2P(CH2)3CH=CH2(1) or t-Bu2P(CH2)9CH=CH2(2) has been achieved using CpMe2Ti(NPt-Bu3) as the precatalyst and B(C6F5)3, [Ph3C][B(C6F5)4], or [PhNMe2H][B(C6F5)4] as the activator. The resulting polymers are shown to incorporate up to 9% of the phosphine comonomer, albeit with reduced catalyst activity and polymer molecular mass. The cause of the catalyst inhibition is also considered in the light of phosphine–activator interactions.
    Canadian Journal of Chemistry 10/2009; 87(11):1620-1624. · 1.01 Impact Factor
  • Jenny S J McCahill, Gregory C Welch, Douglas W Stephan
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    ABSTRACT: The ability of phosphonium borates of the form [R3PH][B(C6F5)4], R2PHC6F4BF(C6F5)2 and R2PHC4H8OB(C6F5)3 as well as the phosphine-boranes R2PC6F4B(C6F5)2 to activate CpTiMe2(NPtBu3) for olefin polymerization was examined via both stoichiometric reactions and catalytic performance. In general these activators resulted in highly active ethylene polymerization catalysts, despite the generation of liberated phosphine donors. Independent experiments in which phosphines were added to the catalyst systems revealed the expected decrease in activity for small phosphines. However in the case of sterically encumbered phosphines, a marked increase in activity was observed. The cause of this increase is considered in the context of the concept of "frustrated Lewis pairs".
    Dalton Transactions 10/2009; · 4.10 Impact Factor
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    ABSTRACT: The phosphines tBu(2)P(CH(2))(3)ECH(2)Ph (E = O (1), S (2)) converted to the corresponding phosphinimines (Me(3)SiN)PtBu(2)(CH(2))(3)ECH(2)Ph, E = O (3), S (4)) which were used to prepared the titanium complexes Cp'TiCl(2)NPtBu(2)(CH(2))(3)ECH(2)Ph, (E = O, Cp' = Cp (5), Cp* (6); E = S, Cp' = Cp (7), Cp* (8)). These species were subsequently methylated to the corresponding dimethyl-derivatives (9)-(12). Activation of (9)-(12) with both B(C(6)F(5))(3) and [Ph(3)C][B(C(6)F(5))(4)] was studied. For example, the [CpTiMe(NPtBu(2)(CH(2))(3)OCH(2)Ph)][MeB(C(6)F(5))(3)] (13) reacted with THF to give [CpTiMe(THF)(NPtBu(2)(CH(2))(3)OCH(2)Ph)][MeB(C(6)F(5))(3)] (14). Similar reactions gave the stable ion pairs [Cp'TiMe(NPtBu(2)(CH(2))(3)XCH(2)Ph)][MeB(C(6)F(5))(3)] (X = O, Cp' = Cp*, (15); X = S Cp' = Cp, (16), Cp*(17)) and [Cp'TiMe(NPtBu(2)(CH(2))(3)XCH(2)Ph)][B(C(6)F(5))(4)] (X = O, Cp' = Cp, (18); Cp*(19); X = S, Cp' = Cp, (20), Cp* (21)). The dihalide complexes (5)-(8), activated with MAO, proved to be ethylene polymerization catalysts of moderate activities. The dialkyl titanium complexes (9)-(12) activated with B(C(6)F(5))(3) or [Ph(3)C][B(C(6)F(5))(4)], gave catalysts that exhibited substantially higher activity and high molecular weight polyethylene. Polymerization at 60 degrees C rather than 30 degrees C significantly increased activity as well. The impact of the hemilabile donor with respect to catalyst activity is discussed. Crystallographic studies of (5) and (6) are reported.
    Dalton Transactions 04/2009; · 4.10 Impact Factor
  • Jenny S J McCahill, Gregory C Welch, Douglas W Stephan
    Angewandte Chemie International Edition 02/2007; 46(26):4968-71. · 11.34 Impact Factor
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    ABSTRACT: The phosphinimines Ph3PNR (R = Ph 1, 2,6-Me2C6H3 2, 3,5-Me2C6H3 3, 2,6-i-Pr2C6H3 4) were prepared and used to generate the species of the form [Li(o-C6H4PPh2NR)]2·Et2O (R = Ph 5, 2,6-Me2C6H3 6, 3,5-Me2C6H3 7, 2,6-i-Pr2C6H3 8). Subsequent reactions with [Rh(μ-Cl)(COD)]2 gave the complexes Rh(COD)(o-C6H4PPh2NR) (R = Ph 9, 2,6-Me2C6H3 10, 3,5-Me2C6H3 11, 2,6-i-Pr2C6H3 12). Similarly, the Ir analogue of 9 (13) was prepared using [Ir(μ-Cl)(COD)]2. The reaction of 9 with (CH2PPh2)2 afforded Rh(PPh2CH2CH2PPh2)(o-C6H4PPh2NPh) (14). Compound 9 was also shown to react with CH2Cl2 to give two products, one of which was confirmed to be [Rh(o-C6H4PPh2NPh)(CH2-o-C6H4PPh2NPh)(μ-Cl)2Rh(COD)] (15). Similar treatment of 10 and 12 with CH2Cl2 showed no reaction, while reaction of 11 with CH2Cl2 gave a mixture of unidentified products. The related imidazole-phosphinimine ligands (N2C3H3)PPh2NR (R = Ph 18, 2,6-Me2C6H3 19) were also prepared. These ligands react with NaH to give the corresponding Na-imidazolate-phosphinimines, 20 and 21, and subsequent reaction with [Rh(μ-Cl)(COD)]2 gave the complexes Rh(COD)((N2C3H2)PPh2NR) (R = Ph 22, 2,6-Me2C6H3 23). The compounds 22 and 23 do not react with CH2Cl2. The effects of steric and electronic modifications to the ligands on oxidative addition of C−Cl bonds are discussed. DFT calculations were performed on the model fragments [Rh((C6H4)PH2NH)] and [Rh((N2C3H2)PH2NH)], and the calculated atomic charges provide some insight into the reactivity of these compounds.
    Organometallics 12/2003; 23(3). · 4.25 Impact Factor