Cyclopentadienone Vanadium(I) Complex: Synthesis, Red/Ox Activity, and Application to Catalytic Transfer Hydrogenation

Cyclopentadienone late transition metal complexes have
exhibited
various catalytic transformation and elementary reactions by transferring
electrons from the metal to ligand, the so-called metal–ligand
cooperation mechanism. Herein, we report a cyclopentadienone low-valent
early transition metal, a vanadium(I), complex. The obtained complex
furnished the most extended CO bond length among all of the
analogous CpO metal complexes, showing a substantial degree of metal-to-ligand
electron transfer. The red/ox activity of the vanadium center in the
cyclopentadienone V(I) complex was confirmed upon the addition of
the proton source to yield the hydroxycyclopentadienyl V(III) complex.
The system was applied to catalytic transfer hydrogenation of carbonyl
compounds, indicating the possible application of the red/ox of the
early transition metals in metal–ligand cooperative organic
transformations.