In this work, a traditional field of organometallic chemistry - the chemistry of cyclopentadienyl ligands - was taken up and further developed with regard to three innovative key topics: The important chemistry of cyclopentadienylmetal complexes was converted from a petrochemical to a renewable raw material source, guaiazulene, as a Cp ligand synthon, exemplary for the electron-rich transition metals of Groups 8-12 (Sec. 3.1). In addition, purely organic salts of the cyclopentadienide anion Cat[Cp] were presented for the first time as versatile one-electron reducing agents and their advantages in comparison to other reducing agents were elaborated by means of the reduction of rylenediimide-based organic semiconductor materials to crystalline radical anion and dianion salts (Sec. 3.2). Finally, a highly selective ortho-dicarboxylation of CH-acid cyclopentadiene, reminiscent of the Kolbe-Schmitt synthesis, was presented, which succeeds using methyl carbonate salts Cat[OCO2Me] as base and CO2 source (Sec. 3.3). Reactivity studies of Cat[Cp] toward CO2-related electrophiles were also the subject of this research (Sec. 3.4). Finally, the fact that methyl carbonate salts with symmetric onium cations can serve as well-crystallizing templates for the synthesis of hitherto poorly accessible metallate complexes was highlighted in detail in section 3.5.
Cyclopentadienyl-SynthonCyclopentadienyl synthonnachwachsende RohstoffeKatalysecatalysisrenewable resourcescarboxylationCarboxylierungElektronentransferelectron transfer