Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes.: X-ray molecular structure of [Zr{η5-C5H4(SiMe2CH2Ph)}(CH2Ph)3]

New silyl substituted monocyclopentadienyl complexes of Zr(IV) were synthesized from the precursor [Zr{eta(5)-C5H4(SiMe2Cl)}Cl-3] (1). The reaction of 1 with the lithium benzamidinate salt Li[C(Ph)(N(SiMe3)}(2)] leads to the complex [Zr{eta(5)- C5H4(SiMe2Cl)}(C(Ph)(N(SiMe3)](2))Cl-2] (2), which decomposes slowly in solution with elimination of SiMe3Cl. Complex 1 reacts with alkyl, amido and alkoxo transfer reagents (4 equiv.) to afford complexes [Zr{eta(5)-C5H4(SiMe2X)}X-3] (X = NMe2 (3), OSiMe3 (4), CH2CM2Ph (5), C6H5 (6), C6F5 (7) and CH2SiMe3 (8)) in good yields. Compounds 6 and 7 retain diethyl ether used as solvent but decompose as soon as they are desolvated under high vacuum conditions. Reaction of 1 with Mg(CH2Ph)(2) . 2THF (4 equiv.) yields the tetrabenzyl complex [Zr{eta(5)-C5H4(SiMe2CH2Ph)}(CH2Ph)(3)] (9), The H-1 and C-13 NMR data of the latter compound are discussed in terms of the non-classical coordination mode of the CH,Ph ligand. The molecular structure of [Zr{eta(5)-C5H4(SiMe2CH2Ph)}(CH2Ph)(3)] 9 has been determined by X-ray diffraction methods. The coordination geometry around the zirconium atom shows a substituted eta(5)-cyclopentadienyl ring and three different benzyl Ligands: a distorted eta(2)-benzyl group; a normal eta(1)-benzyl group; and a benzyl ligand with an intermediate coordination mode. The benzyl fragment bonded to silicon points away from the metal center. 9 crystallized in monoclinic space group P2(1)/c with a = 11.268(3) Angstrom, b = 10.846(3) Angstrom, c = 27.734(6) Angstrom, beta = 100.29(1)degrees, V = 3334.9(15) Angstrom(3) for Z = 4. The tetraalkylated compounds 6, 7 and 9 are excellent precursors for the preparation of the chloro derivatives. Reactions of these complexes with 3 equiv. of HCl gave the corresponding trichloro [Zr{eta(5)-C5H4(SiMe2R)}Cl-3] (R = C6H5 (10), C6F5 (11), CH2Ph (12)). The monochloro [Zr{eta(5)-C5H4(SiMe2CH2Ph)}(CH(2)ph)(2)Cl] (13) and the dichloro derivative [Zr{eta(5)-C5H4(SiMe2CH2Ph)}(CH2Ph)Cl-2] (14) are observed, at 60 degrees C and 90 degrees C, respectively, by NMR experiments in deuterated chloroform. Complexes 10 and 11 also retain coordinated solvent, decomposing slowly when it is removed. 1 and 12 in the presence of MAO as cocatalyst, at 25 degrees C and 1 atm of monomer pressure, cause the polymerization of ethylene with moderate activities, while under similar conditions, polymerization of propylene and styrene proceeds giving only traces of atactic materials. (C) 1997 Elsevier Science S.A.