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Counteranion effects on propylene polymerization rates and stereoselectivities are compared using Cs-symmetric Me2C(Cp)(Flu)ZrMe2 (1; Cp = C5H4,eta5-cyclopentadienyl; Flu = C13H8, eta5-fluorenyl) and C1-symmetric Me2Si(OHF)(CpR*)ZrMe2 (2; OHF = C13H16, eta5-octahydrofluorenyl; CpR* = eta5-3-(-)-menthylcyclopentadienyl) precatalysts activated with the mononuclear and polynuclear perfluoroarylborate, -aluminate, and -gallate cocatalysts/activators B(C6F5)3 (3), B(o-C6F5C6F4)3 (4), Al(C6F5)3 (5), Ph3C+B(C6F5)4- (6) Ph3C+FAl(o-C6F5C6F4)3- (7), Ga(C6F5)3 (8), and recently reported mono- and polymetallic trityl perfluoroarylhalometalates Ph3C+FB(C6F5)3- (9), Ph3C+FB(o-C6F5C6F4)3- (10), (Ph3C+)xFx[Al(C6F5)3]yx- (x = 1, y = 1, 11; x = 1, y = 2, 12; x = 2, y = 3, 13), Ph3C+(C6F5)3AlFAl(o-C6F5C6F4)3- (14), Ph3C+XAl(C6F5)3- (X = Cl, 15; X = Br, 16), and Ph3C+F[Ga(C6F5)3]2- (17). Temperature, propylene concentration, and solvent polarity dependence are surveyed in polymerizations catalyzed by 1 activated with cocatalysts 3-16 and with a 1:2 ratio of Ph3CCl and 5, and with a 1:2 ratio of Ph3CBr and 5, and by 2 activated with 3, 6, 7, 12, and 14. Remarkable stereocontrol with high activities is observed for 1 + 12 and 1 + 14. Polypropylene samples produced using C1-symmetric precatalyst 2 are subjected to microstructural analyses using stochastic models describing the relative contributions of enantiofacial misinsertion and backskip processes. A powerful technique is introduced for calculating interparametric correlation matrices for these nonlinear stochastic models. The collected results significantly extend what is known about ion-pairing effects in the case of Cs-symmetric precatalyst 1 and allow these findings to be applied to the case of C1-symmetric precatalyst 2 as an agent of isospecific propylene polymerization.

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A series of mononuclear and polynuclear trityl (perfluoroaryl)borate, -aluminate, and -gallate reagents, potential cocatalysts/activators for metallocene-mediated olefin polymerization, have been synthesized via fluoride abstraction from trityl fluoride (Ph3CF) by the organo Lewis acid reagents B(C6F5)3 (1), B(o-C6F5C6F4)3 (2), and Al(C6F5)3 (3), by derivatization of Ph3C+FAl(o-C6F5C6F4)3 - (4), and by reaction of trityl fluoride with in situ generated Ga(C6F5)3 (5). Reaction of trityl fluoride with the tris(perfluoroaryl)boranes 1 and 2 yields the trityl tris(perfluoroaryl)fluoroborates Ph3C+FB(C6F5)3 - (6) and Ph3C+FB(o-C6F5C6F4)3 - (7), respectively. The three trityl tris(perfluorophenyl)fluoroaluminates (Ph3C+) x F x [Al(C6F5)3] y x - (x = 1, y = 1, 8; x = 1, y = 2, 9; x = 2, y = 3, 10) can be isolated from the reaction of trityl fluoride with the tris(perfluoroaryl)alane 3 in the appropriate molar ratios. Reaction of the trityl tris(perfluoroaryl)fluoroaluminate 4 with 3 affords the asymmetric fluoro-bridged trityl bis[tris(perfluoroaryl)]aluminate Ph3C+(C6F5)3AlFAl(o-C6F5C6F4)3 - (11), while reaction of the trityl halides Ph3CCl and Ph3CBr with 3 gives the corresponding trityl tris(perfluorophenyl)haloaluminates Ph3C+XAl(C6F5)3 - (X = Cl, 12; X = Br, 13). The isolable, symmetric fluoro-bridged trityl bis[tris(perfluoroaryl)]gallate Ph3C+F[Ga(C6F5)3]2 - (14) is derived from a “one-pot” reaction of trityl fluoride with Ga(C6F5)3, generated in situ from 4 + Ga(CH3)3. Of these new species, compounds 7 and 10−14 were characterized by single-crystal X-ray diffraction. Trityl salts 6−13 react with the C s-symmetric metallocene precatalyst Me2C(Cp)(Flu)ZrMe2 (15:  Cp = C5H4; Flu = C13H8, fluorenyl) to form isolable ion-pair complexes or characterizable mixtures. Species 6 reacts with 15 to generate the known ion pair Me2C(Cp)(Flu)ZrMe+MeB(C6F5)3 - (16), and reaction of 7 with 15 gives the fluoro-bridged dimeric diastereomers [Me2C(Cp)(Flu)ZrMe]2(μ-F)+FB(o-C6F5C6F4)3 - (17). The trityl tris(perfluorophenyl)fluoroaluminates 8−10 all react with 15 to afford mixtures of Me2C(Cp)(Flu)ZrMe+FAl(C6F5)3 - (18) and diastereomeric [Me2C(Cp)(Flu)ZrMe]2(μ-Me)+(C6F5)3AlFAl(C6F5)3 - (19). Asymmetric species 11 cleanly affords the diastereomeric [Me2C(Cp)(Flu)ZrMe]2(μ-Me)+(C6F5)3AlFAl(o-C6F5C6F4)3 - (20) in reaction with the metallocene 15. Adducts of 12 and 13 with the metallocene 15 afford the decomposition products Me2C(Cp)(Flu)ZrCl(C6F5) (21) and [Me2C(Cp)(Flu)Zr(μ2-Br)]2 2+[Al(C6F5)4 -]2 (22), respectively. Complexes 17−22 were characterized by single-crystal X-ray diffraction.