This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.We have succeeded in synthesizing metallabenzenes using an approach that employs pentadienide reagents as the source of the ring carbon atoms. As shown in the scheme below, treatment of (Cl)Ir(PEt3)3 with potassium 2,4-dimethylpentadienide produces the 1-metallacyclohexa-2,4-diene complex 1, via iridium-mediated activation of a C-H bond on the terminus of the eta1-pentadienyl ligand in intermediate A. Compound 1 is then 'dehydrogenated' in two steps: a) removal of the hydride ligand with methyltriflate and b) deprotonation of the alpha-ring carbon with base. The red crystalline product, 'iridabenzene' 2, is obtained in high yield.While some of these reactions mimic those of conventional organic arenes, others differ sharply due to the powerful influence of the transition metal center. From these studies, the guidelines for what constitutes 'aromatic behavior' in metallacycles are beginning to emerge.
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