Darstellung und Reaktivität von {(η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 }Ni(CO)

Synthesis and Reactivity of {(η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 }Ni(CO) The synthesis and reactivity of {(η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 }Ni(CO) ( 6 ) is described. (η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 ( 1a ) reacts with equimolar amounts of Ni(CO) 4 ( 5 ) to afford the dinuclear complex {(η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 }Ni(CO) ( 6 ) in 95% yield. In 6 both phenylethynyl units are η 2 ‐side‐on‐coordinated to the Ni(CO) moiety. When 6 is treated with HX or X 2 (X = Cl, Br) the Ti–C(alkynyl) σ bond is cleaved, and the corresponding titanocene dihalides (η 5 ‐C 5 H 4 SiMe 3 ) 2 TiX 2 ( 7 ) are formed. With PRR′ 2 [ 8a : R = R′ = OMe; 8b : R = C = CPh, R′ = Ph; 8c : R = Ph, R′ = CCPh] 6 reacts by substitution of the nickel‐bonded carbonyl ligand to form {(η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh 2 }Ni(PRR' 2 ) ( 9 ). The reactivity of 9b , which contains a noncoordinated phenylethynyl unit, has been investigated by using Co 2 (CO) 8 ( 10 ) and Fe 2 ‐(CO) 9 ( 13 ). With 10 the compounds {η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 }Ni(CO) ( 6 ), [μ‐(η 2 ‐Ph 2 PCCPh)]Co 2 (CO) 6 ( 11 ) and {[μ‐(η 2 ‐Ph 2 PCCPh)]Co 2 (CO) 5 } 2 ( 12 ) can be obtained. Complex 11 yields upon heating by decarbonylation and dimerization the six‐membered cyclic compound 12 . Whereas, the reaction of 9b with 13 affords {(η 5 ‐C 5 H 4 SiMe 3 ) 2 Ti(CCPh) 2 }Ni(CO) ( 6 ) next to the dinuclear complex Fe 2 (CO) 6 ‐(μ‐PPh 2 )[μ‐(η 1 :η 2 ‐CCPh)] ( 14 ).