Iridium(<scp>iii</scp>) bis(thiophosphinite) pincer complexes: synthesis, ligand activation and applications in catalysis

Linke, Alexander; Decker, David L.; Drexler, Hans‐Joachim; Beweries, Torsten

doi:10.1039/d2dt01633h

Cited by 4 publications

(9 citation statements)

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“…This effect may be viewed as underlying the very different free energies of the two reactions in Figure , which involve the interconversion of hydrido chloride complexes with dihydride and dichloride, respectively. We note that these results are qualitatively consistent with numerous examples of particularly stable five-coordinate d 6 hydrido halide complexes, which play an important role in the chemistry of both pincer-ligated − and nonpincer-ligated − complexes of Ru as well as Rh and Ir.…”

Section: Resultssupporting

confidence: 86%

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Ruthenium Complexes of a Triphosphorus-Coordinating Pincer Ligand: Ru–P Ligand-Substituent Exchange Reactions Driven by Large Variations of Bond Energies

et al. 2023

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The reaction of [(p-cymene)RuCl 2 ] 2 with the triphosphine ligand bis(2di-tert-butylphosphinophenyl)phosphine ( tBu P H PP) results in an unusual exchange reaction in which a chloride ligand and a phosphorus-bound H atom are exchanged ("H−P/Ru−Cl exchange") to give the (chlorophosphine)ruthenium hydride complex ( tBu P Cl PP)RuHCl [1 Cl -HCl; tBu P Cl PP = bis(2-di-tert-butylphosphinophenyl)chlorophosphine]. Density functional theory calculations indicate that the presumed initial product of metalation, ( tBu P H PP)RuCl 2 (1 H -Cl2), undergoes an H−P/Ru−Cl exchange via sequential P-to-Ru α-H migration to give the intermediate ( tBu PPP)RuHCl 2 , followed by Ru-to-P α-Cl migration to give the observed product 1 Cl -HCl (crystallographically characterized). Dehydrochlorination of 1 Cl -HCl under a H 2 atmosphere gives ( tBu P Cl PP)RuH 4 (1 Cl -H4), which then can undergo a second dehydrochlorination and addition of H 2 to give ( tBu P H PP)RuH 4 (1 H -H4). This reaction may proceed via the reverse of the intramolecular exchange by 1 H -Cl2, i.e., loss of H 2 from 1 Cl -H4 to give 1 Cl -H2, which could undergo Cl−P/Ru−H exchange to give ( tBu P H PP)RuHCl (1 H -HCl). Accordingly, the thermodynamics of Cl−P/Ru−H exchange are found to be highly dependent on the nature of the ancillary anionic ligand (H or Cl), which is not directly involved in the exchange. The origin of this thermodynamic dependence can be explained in terms of the high stability of complexes ( R P X PP)RuHCl (X = H, Cl; R = Me, t Bu), in which the hydride is approximately trans to a vacant coordination site and the central phosphine group is approximately trans to the weak-trans-influence chloride ligand. This conclusion has general implications for five-coordinate d 6 complexes, both pincer-and nonpincer-ligated.

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Section: Resultssupporting

confidence: 86%

“…This conclusion is applicable well beyond the present system. Five-coordinate metal hydridochlorides and many closely related complexes are particularly common and stable for a number of d 6 metal centers, including Ir III and Rh III as well as Ru II . − ,− …”

Section: Discussionmentioning

confidence: 99%

Ruthenium Complexes of a Triphosphorus-Coordinating Pincer Ligand: Ru–P Ligand-Substituent Exchange Reactions Driven by Large Variations of Bond Energies

et al. 2023

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“…Their largest turnovers reported in COA/TBE transfer dehydrogenation are given in parentheses. First reports of the complexes are t ‑Bu A : refs and ; i ‑Pr A : ref ; t ‑Bu B : ref ; i ‑Pr B : ref ; t ‑Bu C : ref ; i ‑Pr D : ref ; t ‑Bu E : ref ; i ‑Pr E : ref ; t ‑Bu F : ref ; and i ‑Pr F ′, t ‑Bu G , and i ‑Pr F″ : ref .…”

Section: Introductionmentioning

confidence: 99%

“…Among various methods, including modifying the backbone − and substituents on the phosphorus atoms, − the modification of the linker elements between the phenyl anion core and phosphorus sidearms has been effective. Oxygen-linked complexes t ‑Bu B and i ‑Pr B outperformed the corresponding methylene-linked complexes R A in the COA/TBE transfer dehydrogenation. , The nitrogen-linked complex t ‑Bu C and the sulfur-linked complex i ‑Pr D were also synthesized but found to be less active for COA/TBE transfer dehydrogenation. , The hybrid S/O-linked complex i ‑Pr E is highly efficient in the transfer dehydrogenation of COA, n -alkanes, and heterocycles. , Thus far, the N -alkylated O/N-linked complex i ‑Pr F″ , giving 14700 TONs, has been the best catalyst for the COA/TBE transfer dehydrogenation at 200 °C …”

Section: Introductionmentioning

confidence: 99%

“…46,47 The nitrogen-linked complex t-Bu C and the sulfur-linked complex i-Pr D were also synthesized but found to be less active for COA/TBE transfer dehydrogenation. 48,49 The hybrid S/O-linked complex i-Pr E is highly efficient in the transfer dehydrogenation of COA, n-alkanes, and heterocycles. 50,51 Thus far, the N-alkylated O/N-linked complex i-Pr F″, giving 14700 TONs, has been the best catalyst for the COA/TBE transfer dehydrogenation at 200 °C.…”

Section: ■ Introductionmentioning

confidence: 99%

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Low-Temperature Dehydrogenation of Cyclooctane by Using Pincer Iridium Complexes Bearing an N,N′-Diarylated PNCNP Ligand

2023

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PNCNP pincer iridium complexes possessing arylnitrene linkers (−N(Ar)−) catalyze transfer dehydrogenation of cyclooctane (COA) under low-temperature conditions, giving 200 turnovers at 125 °C using tert-butylethylene (TBE) and 60 turnovers at 50 °C using cyclohexene (CHE) as a sacrificial hydrogen acceptor. Despite prior reports dealing with the synthetic difficulty of pincer iridium complexes bearing di(isopropyl)phosphoramine sidearms, our design using chemically inert (3,5-disubstituted-aryl)nitrene linkers allowed for the successful complexation with iridium. The structural characterization and computational study revealed that steric congestion provided by arylnitrene linkers destabilizes the resting internal alkene adducts, thereby reducing the overall activation barrier of the rate-limiting C–H addition. The steric congestion also hinders undesirable disproportionation of CHE, allowing for its use as an effective hydrogen acceptor. With their straightforward synthesis coupled with fine tunability through the 3,5-substituents on the aryl groups, the N,N′-diarylated PNCNP ligands presented in this work will be a valuable addition to the highly successful PCP pincer framework.

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A Dinuclear Ir(III) Bis(thiophosphinite) Complex Formed by Unusual meta-C–H Activation at a Pincer Ligand

Linke,

Drexler,

Beweries

2024

Organometallics

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Oxidative addition of PC(H)P pincer ligands at late transition metals typically occurs via C−H activation in the 2-position of the ligand, yielding [(PCP)MHX] type pincer complexes (X = monoanionic ligand). We p r e s e n t f o r m a t i o n o f t h e d i n u c l e a r I r ( I I I ) c o m p l e x [( iPr PSCSP iPr )Ir(H)(MeCN) 2 ] 2 [OTf] 2 as a rare example of meta-C−H activation at a pincer ligand.

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Iridium(iii) bis(thiophosphinite) pincer complexes: synthesis, ligand activation and applications in catalysis

Abstract: Iridium(III) bis(thiophosphinite) complexes of the type [(RPSCSPR)Ir(H)(Cl)(py)] (RPSCSPR = κ3-(2,6-SPR2)C6H3) (R = tBu, iPr, Ph) can be prepared from the ligand precursors 1,3-(SPR2)C6H4 by C-H activation at Ir [Ir(COE)2Cl]2 or...

Cited by 4 publications

References 64 publications

Ruthenium Complexes of a Triphosphorus-Coordinating Pincer Ligand: Ru–P Ligand-Substituent Exchange Reactions Driven by Large Variations of Bond Energies

Ruthenium Complexes of a Triphosphorus-Coordinating Pincer Ligand: Ru–P Ligand-Substituent Exchange Reactions Driven by Large Variations of Bond Energies

Low-Temperature Dehydrogenation of Cyclooctane by Using Pincer Iridium Complexes Bearing an N,N′-Diarylated PNCNP Ligand

A Dinuclear Ir(III) Bis(thiophosphinite) Complex Formed by Unusual meta-C–H Activation at a Pincer Ligand

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