Application of Hemilabile Ligands to “At-Metal Switching” Hydrogenation Catalysis

Zhang, Yu; Woods, Toby J.; Rauchfuss, Thomas B.

doi:10.1021/acs.organomet.0c00562

Cited by 5 publications

(3 citation statements)

References 44 publications

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“…Absence of the S-Pt coordination in this complex was already evident from the shape of the 1 H-decoupled 19 F-NMR spectrum signal at -100.1 ppm, appearing as a singlet rather than a triplet as in 6[NTf2], and was also confirmed by the absence of 19 F-195 Pt correlation. Similar to the aliphatic system, our subsequent attempts to obtain the (κ3-P Ph SP)Pt(Solv) (8) complex by chloride abstraction from 7[NTf2] were unsuccessful (Scheme 5).…”

Section: Scheme 3: Synthesis Of Complexes [Ptcl2] and [Ptcl] Complexe...mentioning

confidence: 99%

Sulfonium-Pincer Ligands Flexibility in Pt(II) Complexes

Barel

Subramaniyan

et al. 2022

Preprint

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The coordination chemistry of sulfonium cations, dormant since the early eighties, was recently revived when we reported the synthesis and characterization of the first Rh(I) and Pt(II) pincer sulfonium complexes. With the Pt(II) complexes, we had noticed the hemilability of our sulfonium pincer ligands, further explored here. This hemilability led to mononuclear bidentate complexes with both the aromatic and aliphatic sulfonium ligands. With the latter, due to its flexibility, dimeric structures of two different kinds were also allowed. The more rigid aromatic backbone adopted only a mononuclear bidentate mode, leading to a dynamic equilibrium between two asymmetric geometries. Computational study of this process predicted a local energy minimum for a pincer sulfonium-PtCl complex. However, the activation energy of its formation, as a possible intermediate, was found to be too high and indeed was not observed experimentally. Nevertheless, such PtCl complex was prepared and characterized by XRD. Although its S-Pt bond was significantly shorter than in its PtMe analog, the former was easily dissociated in coordinating solvents. It seems that lowering the dz2 orbital in this complex by strong π-back donation, renders the Pt(II) nucleus more susceptible to nucleophilic attacks. This comprehensive study should lay the ground for future applications of pincer sulfonium-Pt(II) complexes in π-acid catalysis.

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Section: Scheme 3: Synthesis Of Complexes [Ptcl2] and [Ptcl] Complexe...mentioning

confidence: 99%

Sulfonium-Pincer Ligands Flexibility in Pt(II) Complexes

Barel

Subramaniyan

et al. 2022

Preprint

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“…In fact, these weak donors temporarily protect the active metal center from undesired side reactions until the substrate is incorporated into the coordinating sphere of the metal. Complexes of such ligands have been applied to catalytic hydrogenation, carbonylation, hydroformylation, allylation, epoxidation, and numerous other transformations . Such a hemilabile character has often been found to be the key to catalytic activity of POP pincer complexes .…”

Section: Introductionmentioning

confidence: 99%

Sulfonium-Pincer Ligands Flexibility in Pt(II) Complexes

Barel

Subramaniyan

et al. 2023

Organometallics

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The coordination chemistry of sulfonium cations, dormant since the early nineties, was recently revived when we reported the synthesis and characterization of the first Rh(I) and Pt(II) pincer-sulfonium complexes. With the Pt(II) complexes, we had noticed the hemilability of our sulfonium-pincer ligands further explored here. This hemilability led to mononuclear bidentate complexes with both the aromatic and aliphatic sulfonium ligands. With the latter, due to its flexibility, dimeric structures of two different kinds were also allowed. The more rigid aromatic backbone adopted only a mononuclear bidentate mode, leading to a dynamic equilibrium between two asymmetric geometries. Computational study of this process predicted a local energy minimum for a pincer-sulfonium−PtCl complex. However, the activation energy of its formation, as a possible intermediate, was found to be too high and indeed was not observed experimentally. Nevertheless, such a PtCl complex was prepared and characterized by XRD. Although its S−Pt bond was significantly shorter than in its PtMe analogue, the former was easily dissociated in coordinating solvents. It seems that lowering the d z 2 orbital in this complex by strong π back-donation renders the Pt(II) nucleus more susceptible to nucleophilic attacks. This comprehensive study should lay the ground for future applications of pincersulfonium−Pt(II) complexes in π-acid catalysis.

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“…While separate signals are observed for [ 1 ] + and excess pyridine, statistical exchange does occur when [ 1 ] + is treated with py- d 5 (Figure S21). Naturally, [Rh(py) 4 ]BAr F 4 is highly reactive toward oxidants: 2 equiv of trityl chloride converts [ 1 ] + into the well-known trans -[RhCl 2 (py) 4 ] + …”

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confidence: 99%

Homoleptic Rhodium Pyridine Complexes for Catalytic Hydrogen Oxidation

2021

Self Cite

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The homoleptic rhodium pyridine complex [Rh(py)4]+ ([1]+) is prepared from simple precursors. Lacking good π-acceptor ligands but being sterically protected, [1]+ reversibly oxidizes to colorless [Rh(py)4(thf)2]2+. This monomeric S = 1/2 Rh(II) complex activates H2 to give [HRh(py)4L]2+, which can also be generated by protonation of [1]+. The Rh(III)–H bond is weak, being susceptible to H atom abstraction as well as deprotonation. These results underpin a novel catalytic system for the oxidation of H2 by ferrocenium.

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Application of Hemilabile Ligands to “At-Metal Switching” Hydrogenation Catalysis

Cited by 5 publications

References 44 publications

Sulfonium-Pincer Ligands Flexibility in Pt(II) Complexes

Sulfonium-Pincer Ligands Flexibility in Pt(II) Complexes

Sulfonium-Pincer Ligands Flexibility in Pt(II) Complexes

Homoleptic Rhodium Pyridine Complexes for Catalytic Hydrogen Oxidation

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