SYNTHESIS AND REACTIVITY OF ((ETA-5-C5H4SIME3)2TI(C-EQUIVALENT-TO-CPH)2)NI(CO)

The synthesis and reactivity of {(eta-5-C5H4SiMe3)2Ti-(C=CPh)2}Ni(CO) (6) is described. (eta-5-C5H4SiMe3)2Ti(C=CPh)2 (1a) reacts with equimolar amounts of Ni(CO)4 (5) to afford the dinuclear complex {(eta-5-C5H4SiMe3)2Ti-(C=CPh)2}Ni(CO) (6) in 95% yield. In 6 both phenylethynyl units are eta-2-side-on-coordinated to the Ni(CO) moiety. When 6 is treated with HX or X2 (X = Cl, Br) the Ti - C(alkynyl) sigma-bond is cleaved, and the corresponding titanocene dihalides (eta-5-C5H4SiMe3)2TiX2 (7) are formed. With PRR2' [8a: R = R' = OMe; 8b: R = C=CPh, R' = Ph; 8c: R = Ph, R' = C=CPh] 6 reacts by substitution of the nickel-bonded carbonyl ligand to form {(eta-5-C5H4SiMe3)2Ti(C = CPh)2}Ni(PRR22') (9). The reactivity of 9b, which contains a noncoordinated phenylethynyl unit, has been investigated by using CO2(CO)8 (10) and Fe2(CO)9 (13). With 10 the compounds {(eta-5-C5H4SiMe3)2Ti(C=CPh)2}Ni(CO) (6), [mu-(eta-2-Ph2PC=CPh)]Co2(CO)6 (11) and {mu-(eta-2-Ph2PC=CPh)]Co2(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 {(eta-5-C5H4SiMe3)2Ti(C=CPh)2}Ni(CO) (6) next to the dinuclear complex Fe2(CO)6-(mu-PPh2)[mu-(eta-1:eta-2-C=CPh)] (14).