title: Characterization of the low-energy electronic excited states of benzoyl-substituted ruthenocenes.
abstract: Electronic absorption and resonance Raman spectral studies of benzoylruthenocene (BRc) and 1,1'-dibenzoylruthenocene (DRc) indicate that the low-energy electronic excited states of these 4d(6) metallocenes possess metal-to-ligand charge transfer (MLCT) character. While this MLCT contribution should weaken the metal-ring bonding in the excited state, neither compound is photosensitive in nonhalogenated solvents such as methanol, acetonitrile, and cyclohexane. In contrast, irradiating BRc and DRc in the good electron-accepting solvent, carbon tetrachloride, results in ring loss via a pathway that appears to originate from a charge-transfer-to-solvent excited state. Both metallocenes function as photoinitiators for the anionic polymerization of ethyl 2-cyanoacrylate, and the kinetics and mechanism of this process have been investigated. Comparing the present results on BRc and DRc with those reported earlier for the corresponding benzoyl-substituted ferrocene compounds reveals some interesting commonalities and differences between the excited-state properties of these 3d and 4d metallocenes.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Cynthia T
authors.initials: CT
authors.lastname: Sanderson
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Quinlan
authors.forename: Richard C
authors.initials: RC
authors.lastname: Conover
authors.forename: Michael K
authors.initials: MK
authors.lastname: Johnson
authors.forename: Michael
authors.initials: M
authors.lastname: Murphy
authors.forename: Richard A
authors.initials: RA
authors.lastname: Dluhy
authors.forename: Charles
authors.initials: C
authors.lastname: Kutal
mesh_terms: D000465:Algorithms; D001565:Benzoates / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005296:Ferrous Compounds / Q000737:chemistry*; D000075163:Metallocenes; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010777:Photochemistry; D012428:Ruthenium / Q000737:chemistry*; D013059:Spectrum Analysis, Raman
chemical_list: D001565:Benzoates; D005296:Ferrous Compounds; D000075163:Metallocenes; D009942:Organometallic Compounds; C016721:ruthenocene; D012428:Ruthenium; C004998:ferrocene