221679-92-1Relevant academic research and scientific papers
Reactivity studies of the zirconium alkylidene complexes [η5-C5H3-1,3-(SiMe2CH 2PPri2)2]Zr=CHR(C1) (R = Ph, SiMe3)
Fryzuk, Michael D.,Duval, Paul B.,Mao, Shane S. S. H.,Rettig, Steven J.,Zaworotko, Michael J.,MacGillivray, Leonard R.
, p. 1707 - 1716 (1999)
Reactivity studies of the zirconium alkylidene complexes [P2Cp]Zr=CHR(Cl) (1a, R = Ph; 1b, R = SiMe3; [P2Cp] = η5-C5H3-1,3-(SiMe2CH 2PPri2)2) are described. The reaction of 1 with ethylene follows second-order kinetics to give the ethylene complex [P2Cp]Zr(η2-C2H4)Cl (2), the structure of which was determined by X-ray crystallography. Addition of acetone to 1 generates the alkene RCH=CMe2, although the anticipated Zr oxo species could not be isolated from this reaction. An insertion of CO into the Zr=C bond of 1 yields the ketene complex [P2Cp]Zr(η2-C,O-OC=CHR)Cl (3), while the reaction with tert-butyl isocyanide gives the analogous ketenimine complex [P2Cp]Zr(η2-C,N-ButNC=CHR)Cl (4). The structure of ketene 3a (R = Ph), determined by X-ray diffraction, exhibits the E geometry, with the position of the ketene unit with respect to the ancillary [P2Cp] ligand being opposite to that in the configuration of the precursor alkylidene 1a. The ketene complex 3 reacts with ethylene to give [P2Cp]Zr(η2-C,O-CH2CH 2C(O)=CHR)Cl (5). The molecular structure of 5b (R = SiMe3) was obtained by X-ray diffraction and reveals a five-membered zirconaoxacycle arising from the insertion of ethylene into the Zr-C bond of the ketene, which is subsequently coordinated to the metal as an enolate ligand. 5 undergoes a final insertion reaction with CO to give the asymmetric η2-acyl-ylide complex 6. For each reaction detailed above, dissociation of a labile pendant phosphine donor provides an open site for reactivity.
