ZIRCONADIHYDROFURAN COMPLEXES - PREPARATION, STRUCTURE AND REACTIVITY

The zirconocene alkyne complexes Cp(2)Zr(THF)(Me(3)SiC=CSiMe(3)) (1) and Cp(2)Zr(py)(Me(3)SiC=CSiMe(3)) (2) react with acetone to yield the new zirconadihydrofurane complex Cp(2)Zr-O-C(Me(2))-C(SiMe(3))=C(SiMe(3)) (3). Reaction of 3 with tolan gives, under substitution of the alkyne moiety, a further dihydrofurane compound Cp(2)Zr-O-C(Me(2))-C(Ph)=C(Ph) (4). Complexes 3 and 4 are characterized by NMR and X-ray structure analyses. They are compared with the known titanocene complex Cp(2)Ti-O-C(Me(2))-C(Ph)=C(Ph) (5) to study the influence of the metals M = Ti, Zr and the substituents R = Ph, SiMe(3) in selected metalladihydrofuranes Cp(2)M-O-C(Me(2))-C(R)=C(R). Although the structures of complexes 3 and 4 are similar, the complexes display different reactivities. Thus 3 is capable of reacting with tolan, CO2 and water at room temperature, while 4 is inactive towards these compounds under the same conditions.