ELECTRON-DEFICIENT VANADIUM(III) ALKYL AND ALLYL COMPLEXES WITH AMIDINATE ANCILLARY LIGANDS

Vanadium(III) amidinate complexes (amidinate)(2)VCl and (amidinate)VCl 2(THF)(2) were prepared for two different amidinate ligands, [PhC(NSiM e3)(2)](-) and [t-BuC(Ni-Pr)(2)](-). These served as precursors for am idinate V(III) alkyl and allyl derivatives. The allyl ligand in (amidi nate)(2)V(allyl) is eta(3)-bound, indicating that the amidinates act a s four-electron anionic ligands. The 12-electron alkyl complex [PhC(NS iMe3)(2)](2)VMe catalyzes the slow oligomerization of ethene to linear olefins at 80 degrees C. The bis-allyl complex [t-BuC(Ni-Pr)(2)]V(eta (3)-allyl)(2) was prepared and structurally characterized, but its ana logue with the [PhC(NSiMe3)(2)] ligand already decomposes around -30 d egrees C, This shows that the substituent pattern of the amidinate anc illary ligand can strongly affect the stability of organometallic deri vatives.