Metal-to-metal charge-transfer in Cp2Ti(C2Fc)2complexes: What is the impact of replacing Cp with indenyl?

PAC Gym

Charge-transfers, e.g. metal-to-ligand charge-transfer (MLCT) and metal-to-metal charge-transfer (MMCT) are interesting from both a fundamental perspective and for possible applications in dye-sensitized solar cells (DSSC). Because DSSCs use colorless TiO2 as the semiconductor, they require a sensitizer to absorb light in the visible region. The N-719 dye typically used in DSSCs incorporates ruthenium, a rare and expensive transition metal. Within these complexes, the MLCT excited state injects an electron into the conduction band of the TiO2 semiconductor. MMCT states are not only of fundamental interest, but also useful in the search for alternative inexpensive dyes and photocatalysts. Specifically, several groups have begun researching MMCT in solid state M-O-M’ architectures involving TilV acceptors and Fell donors. Our interest in electron transfer through alkynyl bridged organometallic frameworks led us to investigate structures with organic bridges between Fell and TiIV, namely complexes of the type RCp2Ti(C2Fc)2, where RCp can be a variety of substituted cyclopentadienyl ligands. Recently our group has been interested in the impact of substituting Cp with indenyl in these complexes. Therefore, we report the synthesis and characterization of these indenyl complexes in order to understand the effect of this substitution.