Electron-deficient vanadium(III) alkyl and allyl complexes with amidinate ancillary ligands

Vanadium(III) amidinate complexes (amidinate)(2)VCl and (amidinate)VCl2(THF)(2) were prepared for two different amidinate ligands, [PhC(NSiMe3)(2)](-) and [t-BuC(Ni-Pr)(2)](-). These served as precursors for amidinate V(III) alkyl and allyl derivatives. The allyl ligand in (amidinate)(2)V(allyl) is eta(3)-bound, indicating that the amidinates act as four-electron anionic ligands. The 12-electron alkyl complex [PhC(NSiMe3)(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 analogue with the [PhC(NSiMe3)(2)] ligand already decomposes around -30 degrees C, This shows that the substituent pattern of the amidinate ancillary ligand can strongly affect the stability of organometallic derivatives.