Leforestier, Baptiste (2020) Synthesis and organometallic chemistry of rhodium and iridium complexes of macrocyclic PCP and POCOP pincer ligands. PhD thesis, University of Warwick.

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Abstract

Conferring high thermal stability and supporting a broad range of metal-based reactivity, mer-tridentate “pincer” ligands have become ubiquitous in contemporary organometallic chemistry and transformed homogeneous catalysis. Phosphine-based systems bearing a central aryl donor, derived from meta-xylene (PCP) or resorcinol (POCOP), are archetypical examples and complexes of rhodium and iridium have in particular found successful applications in inert bond activation reactions, with the catalytic dehydrogenation of alkanes most remarkable. Motived by the desire to further our understanding of these processes, the objective of this project was to explore the organometallic chemistry of macrocyclic PCP and POCOP pincer complexes featuring mechanically interlocked hydrocarbon substrates: [2]rotaxane and [2]catenanes. The interwoven topology of these systems was chosen as a means to circumvent problems associated with weak metal hydrocarbon interactions and provide a well-defined platform for interrogating their subsequent activation.

The multistep synthesis of macrocyclic POCOP-14’ and PCP-14’ proligands is reported herein, using racemic or asymmetric procedures, respectively. These proligands can be readily metalated and homologous series of MI(CO) and MIIICl2(CO) derivatives (M = Rh, Ir) were isolated and fully characterised in solution and the solid state. The latter were critically evaluated as precursors for the construction of interlocked 1,3-diyne derivatives by Grignard-mediated alkynylation, decarbonylation, and C(sp)–C(sp) bond reductive elimination. Using this strategy, [Rh(POCOP-14)(Ar’C4Ar’)] (Rh-25o, Ar’ = 3,5-tBu2C6H3) was most notably isolated and its dynamic behaviour and reactivity comprehensively studied. This interlocked complex remarkably displays reversible C(sp)–C(sp) bond activation, but under carefully chosen conditions the axle can be reduced all the way to the corresponding 1,4-diarylbut-1-ene.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Ligands (Biochemistry), Organometallic chemistry, Chemical bonds
Official Date:	January 2020
Dates:	Date Event January 2020 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Chaplin, Adrian
Format of File:	pdf
Extent:	211 leaves : illustrations (some colour)
Language:	eng

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