Efficient Photodissociation of Anions from Benzoyl-Functionalized Ferrocene Complexes

• DOI: 10.1021/ic990173t
• Publication Date: 2002-07-26T05:34:40Z
• Authors: Yoshikazu Yamaguchi; Charles Kutal
• Keywords: Cationic polymerization; Quantum yield

Spectroscopic and photochemical studies of several benzoyl-functionalized ferrocene complexes in nonaqueous solvents are reported. Bands observed above 300 nm the electronic absorption spectrum unsubstituted complex, Fe(eta(5)-C(5)H(5))(2), assigned to ligand field transitions shift longer wavelengths intensify upon introduction a benzoyl group into one or both cyclopentadienide rings. Such behavior suggests that these have acquired some charge-transfer character. Visible-light (546 nm) irradiation 1,1'-dibenzoylferrocene, III, dissolved CH(3)CN, CH(3)OH, ethyl alpha-cyanopropionate causes ring-metal cleavage produce benzoylcyclopentadienide ion, C(6)H(5)C(O)C(5)H(4)(-), corresponding half-sandwich cationic Fe[(eta(5)-C(5)H(4))C(O)C(6)H(5)](S)(3)(+) (S is solvent). The disappearance quantum yield, phi(dis), for III 0.45 CH(3)OH 0.28 unaffected by presence O(2), added H(2)O (10 000 ppm), methanesulfonic acid (30 ppm). 1,1'-Dibenzoylferrocenes containing substitutents on phenyl rings undergo photoinduced with phi(dis) values very similar while monobenzoylferrocenes appreciably less photoreactive. A mechanism accommodates discussed. In addition, previous suggestion concerning role photoinitiated anionic polymerization an alpha-cyanoacrylate monomer reconsidered light present study.