The Quest for Double Vicinal C-H Bond Activation on the (eta(5):eta(5)-Fulvalene)diiridium Platform: Syntheses and Structures of (eta(5):eta(5)-Fulvalene)Ir-2(ortho-mu-C6H4)(CO)(2)(Ir-Ir) and Related Complexes

Judith Baumgartner, Robert G. Bergmann, Berndt Kayser, Theodore P. Klupinski, Yong Kwang Park, K. Peter C. Vollhardt, Michael J. West, Bolin Zhu

Research output: Contribution to journalArticle

Abstract

The fulvalene diiridium platform was scrutinized for its potential to effect double vicinal C-H activation of C 6 H 6 and C 6 H 12 , respectively. For this purpose, an improved preparation of Fv[Ir(CO) 2 ] 2 was developed, and the syntheses of the new complexes FvIr(CO) 2 Ir(CO)(η 2 -C 6 F 6 ), Fv[Ir(CO)(η 2 -C 6 F 6 )] 2 , Fv[Ir(CH 2 =CH 2 ) 2 ] 2 (X-ray), Fv[Ir(PMe 3 )(H) 2 ] 2 (X-ray), and (2,2′,3,3′-tetra- tert -butylFv)[Ir(CO) 2 ] 2 were accomplished. When irradiated in C 6 H 6 , these molecules succeeded to varying degrees, and best for (2,2′,3,3′-tetra- tert -butylFv)[Ir(CO) 2 ] 2 , in the double metalation of the aromatic ring to engender ligating Ir 2 (ortho - μ -C 6 H 4 )(CO) 2 (Ir - Ir) moieties, in addition to their precursor mono(phenyliridium hydride) constructs. A competing photochemical pathway is evident by the formation of diastereomers of Fv (or 2,2',3,3'-tetra- tert -butylFv) [Ir(CO)(Ph)(H)] 2 and the resulting dehydrogenated ligated [Ir(CO)(Ph)] 2 (Ir - Ir). The structures of FvIr 2 (ortho - μ -C 6 H 4 )(CO) 2 (Ir - Ir) and trans -Fv[Ir(CO)(Ph)] 2 (Ir - Ir) were corroborated by X-ray analyses. Efforts to realize C-H bond activations with C 6 H 12 generally failed or fared very poorly, with the exception of the tert -butylFv system, which enabled single, but not further, insertion to give (2,2′,3,3′-tetra- tert -butylFv)[Ir(CO)(Cy)(H)][Ir(CO) 2 ] in 34% yield. To explore the relevant chemistry of phenyl- and alkyliridium species attached to Fv, several such derivatives were made by independent routes, adding knowledge to the fundamental behavior of this category of molecules. Where appropriate and for comparative purposes, similar reactions were performed on the corresponding Cp- and 1,2-di- tert -butylCpIr(CO) 2 relatives.

Original languageEnglish
Pages (from-to)2409-2429
Number of pages21
JournalSynthesis
Volume51
Issue number11
DOIs
Publication statusPublished - 2019

Keywords

  • benzyne
  • C-H activation
  • dinuclear complexes
  • iridium
  • photochemistry

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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