Diversity in weakly coordinating anions. Mono- and polynuclear halo(perfluoroaryl)metalates as cocatalysts for stereospecific olefin polymerization: Synthesis, structure, and reactivity

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+) F-x(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 tritylbis[tris(perfluoroaryl)]aluminate Ph3C+(C6F5)(3)AlFAl(o-C6F5C6F4)(3)(-) ( 11), while reaction of the trityl halides Ph3CCl and Ph3CBr with 3 gives the corresponding trityl tris( perfluorophenyl) haloaluminates Ph3C+ XA;(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)(A-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)(A-Me)(+)(C6F5) (AlFAl)-Al-3(C6F5)(3)(-) (19). Asymmetric species 11 cleanly affords the diastereomeric [Me2C(Cp)(Flu)ZrMe] 2(A-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(mu(2)- Br)](2) (2+)[Al(C6F5)(4)(-)](2) (22), respectively. Complexes 17-22 were characterized by single-crystal X- ray diffraction.