Stabilisierung niederkoordinierter M(CO)-Bausteine: Synthese und Reaktivität von {(η5-C5H4SiMe3)2Hf(CCPh)2}M(CO) (M = Ni, Co)

Abstract The synthesis and reactivity of the dinuclear compounds {L 2 Hf(CCPh) 2 M}(CO) (L = η 5 -C 5 H 4 SiMe 3 ; M = Ni: III ; M = Co: V ) are described. The organometallic diyne PhCCL 2 HfCCPh ( I ) reacts with Ni(CO) 4 ( II ) or CO 2 (CO) 8 ( IV ) to afford in high yields III or V , respectively. In III and V , both phenylethynyl units are η 2 -side- on coordinated to M(CO) building blocks. Along with the paramagnetic complex V , compound L 2 Hf(CCPh) [μ-(η 2 -CCPh)Co 2 (CO) 6 ] (VI) can be isolated. Reaction of VI with more CO 2 (CO) 8 ( IV ) yields the compound L 2 Hf[μ-(η 2 -C CPh)Co 2 (CO) 6 ] 2 ( VII ). The reaction of L 2 M(CCR) 2 (M = Hf, R = Ph: Ia ; M = Ti, R = Ph: Ib ; M = Ti, R = SiMe 3 : Ic ) with Fe 2 (CO) 9 ( VIII ) yields L 2 M[(η 2 -CCR)Fe(CO) 4 ] 2 (M = Hf, R = Ph: IXa ; M =Ti, R = Ph: IXb ; M = Ti, R = SiMe 3 : IXc ). In IX each of the two CCR groups is η 2 -side-on coordinated to the 16-electron fragment Fe(CO) 4 . When III is treated with P(OR) 3 (R = CH 3 : Xa ; R = i C 3 H 7 : Xb ) carbonyl substitution is observed to form {L 2 Hf (CCPh) 2 }Ni[P(OR) 3 ] (R = CH 3 : XIa ; R = i C 3 H 7 : XIb ). The identity of all new compounds is confirmed by analytical and spectroscopic (IR, 1 H NMR, 13 C NMR, 31 P NMR, MS) data. Additionally, the structures of I and V were established by X-ray diffraction.