The photosubstitution reactivity of Mo(CNPh)6 was investigated by studying the effects of nucleophile and nucleophile concentration. Substitution quantum yields were identical for pyridine and PPh3 as nucleophiles. Between 0.1 and 4 × 10-4 M pyridine, there was no change in quantum yield. These observations suggest that photosubstitution in Mo(CNph)6 is dissociative in character, not associative as previously thought. Photoinduced electron transfer from Mo(CNPh)6 to chloroform, producing [Mo(CNPh)6Cl]+, was also measured. While photosubstitution is wavelength independent, photoinduced electron transfer quantum yields are wavelength dependent. The electron transfer quantum yield is highest at 313 nm (0.77) and decreases to a constant value of 0.28 at 436 nm. It is proposed that this evidence supports a 'hot' electron transfer process, where electron transfer occurs prior to vibrational relaxation into the metal-to-ligand charge transfer (MLCT) manifold.
|Number of pages||5|
|Journal||Coordination Chemistry Reviews|
|Publication status||Published - 2002|
- 'Hot' electron transfer
- Photosubstitution reactivity