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(NSiMe 3 ) 2 ] - and [ t -BuC(N i -Pr) 2 ] - . These served as precursors for amidinate V(III) alkyl and allyl derivatives. The allyl ligand in (amidinate) 2 V(allyl) is η 3 -bound, indicating that the amidinates act as four-electron anionic ligands. The 12-electron alkyl complex [PhC(NSiMe 3 ) 2 ] 2 VMe catalyzes the slow oligomerization of ethene to linear olefins at 80 °C. The bis-allyl complex [ t -BuC(N i -Pr) 2 ]V(η 3 -allyl) 2 was prepared and structurally characterized, but its analogue with the [PhC(NSiMe 3 ) 2 ] ligand already decomposes around −30 °C. This shows that the substituent pattern of the amidinate ancillary ligand can strongly affect the stability of organometallic derivatives.