New alkenyl-substituted group 4 C-ansa-metallocene complexes. Reactivity of the substituent at the carbon ansa bridge

The allyl-substituted group 4 metal complexes [M{(R)CH(η5-C5Me4)(η5-C5H4)}Cl2] [M = Ti, R = CH2CHdouble bond; length as m-dashCH2, (2); R = CH2C(CH3)double bond; length as m-dashCH2 (3); M = Zr, R = CH2CHdouble bond; length as m-dashCH2 (4), R = CH2C(CH3)double bond; length as m-dashCH2 (5)] have been synthesized by the reaction of allyl ansa -magnesocene derivatives and the tetrachloride salts of the corresponding transition metal. The dialkyl complexes View the MathML source[M(R)CH(η5-C5Me4)(η5-C5H4)R2′] [M = Ti, R = CH2=CHCH2, R′ = Me (6), R′ = CH2Ph (7); R = CH2C(CH3)double bond; length as m-dashCH2, R′ = Me (8), R′ = CH2Ph (9); M = Zr, R = CH2CHdouble bond; length as m-dashCH2, R′ = Me (10), R′ = CH2Ph (11); R = CH2C(CH3)double bond; length as m-dashCH2, R′ = Me (12), R′ = CH2Ph (13)] have been synthesized by the reaction of the corresponding ansa-metallocene dichloride complexes 2–5 and two molar equivalents of the alkyl Grignard reagent. Compounds 2–5 reacted with H2 under catalytic conditions (Wilkinson’s catalyst or Pd/C) to give the hydrogenation products [M{(R)CH(η5-C5Me4)(η5-C5H4)}Cl2] [M = Ti and R = CH2CH2CH3 (14) or R = CH2CH(CH3)2 (15); M = Zr and R = CH2CH2CH3 (16) or R = CH2CH(CH3)2 (17)]. The reactivity of 2–5 has also been tested in hydroboration and hydrosilylation reactions. The hydroboration reactions of 3, 4 and 5 with 9-borabicyclo[3.3.1]nonane (9-BBN) yielded the complexes [M{(9-BBN)CH2CH(R)CH2CH(η5-C5Me4)(η5-C5H4)}Cl2] [M = Ti and R = H (18); M = Zr and R = H (19) or R = CH3 (20)]. The reaction with the silane reagents HSiMe2Cl gave the corresponding [M{ClMe2SiCH2CHRCH2CH(η5-C5Me4)(η5-C5H4)}Cl2] [M = Ti and R = H (21); M = Zr and R = H (22) or R = CH3 (23)]. The reaction of 22 with t-BuMe2SiOH produced a new complex [Zr{t-BuMe2SiOSi(Me2)CH2CH2CH2CH(η5-C5Me4)(η5-C5H4)}Cl2] (24) through the formation of Si–O–Si bonds. On the other hand, reactivity studies of some zirconocene complexes were carried out, with the insertion reaction of phenyl isocyanate (PhNCO) into the zirconium–carbon σ-bond of [Zr{(n-Bu)CH(η5-C5Me4)(η5-C5H4)}2Me2] (25) giving [{(n-Bu)CH(η5-C5Me4)(η5-C5H4)]}Zr{Me{κ2-O,N-OC(Me)NPh}] as a mixture of two isomers 26a–b. The reaction of [Zr{(n-Bu)(H)C(η5-C5Me4)(η5-C5H4)}(CH2Ph)2] (27) with CO also provided a mixture of two isomers [{(n-Bu)CH(η5-C5Me4)(η5-C5H4)]}Zr(CH2Ph){κ2-O,C-COCH2Ph}] 28a–b. The molecular structures of 4, 11, 16 and 17 have been determined by single-crystal X-ray diffraction studies.