Properties and Reactivities of Zwitterionic Platinum(II)-ate Complexes Generated by Transforming Coordination of an Alkyne–Bisphosphine Ligand

Okamoto, Kazuhiro; Sasakura, Kohei; Funasaka, Satoshi; Watanabe, Hiiro; Suezaki, Masahiro; Ohe, Kouichi

doi:10.1021/acs.organomet.0c00759

Cited by 3 publications

(3 citation statements)

References 48 publications

(19 reference statements)

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“…Taking into account the highly electron-rich character of our C , C , C -pincer ligand, we considered that cationic phosphonium ylide core Pd(II) complexes [ 2 – 4 ](OTf) could serve as valuable precursors for the formation of zwitterionic metalate species containing positively charged fragments more or less distant from the metal atom . To validate this proposal, we first tried the reaction of [ 2 ](OTf) with 1 equiv of (allyl)MgBr in THF with the aim to isolate the corresponding η 1 -allyl Pd complex, as such species were reported to be the key intermediates in catalytic allylation of aldehydes with Bu 3 Sn(allyl). , Although a clean formation of a new complex 5 with a 31 P NMR signal at δ P 29.8 ppm slightly shifted to high field compared to [ 2 – 4 ](OTf) was observed after 2 h at RT (Scheme , top), no spectroscopic evidence for the presence of the allyl moiety was obtained.…”

Section: Resultsmentioning

confidence: 99%

Direct Access to Palladium(II) Complexes Based on AnionicC,C,C-Phosphonium Ylide Core Pincer Ligand

et al. 2021

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The reaction of readily available imidazolium−phosphonium salt [MesIm(CH 2 ) 3 PPh 3 ](OTf) 2 with PdCl 2 in the presence of an excess of Cs 2 CO 3 afforded selectively in one step the cationic Pd(II) complex [(C,C,C)Pd(NCMe)]-(OTf) exhibiting an LX 2 -type NHC-ylide-aryl C,C,C-pincer ligand via formal triple C−H bond activation. The replacement of labile MeCN in the latter by CNtBu and CO fragments allowed to estimate the overall electronic properties of this phosphonium ylide core pincer scaffold incorporating three different carbon-based donor ends by IR spectroscopy, cyclic voltammetry, and molecular orbital analysis, revealing its significantly higher electron-rich character compared to the structurally close NHC core pincer system with two phosphonium ylide extremities. The pincer complex [(C,C,C)Pd(CO)](OTf) represents a rare example of Pd(II) carbonyl species stable at room temperature and characterized by X-ray diffraction analysis. The treatment of isostructural cationic complexes [(C,C,C)Pd(NCMe)](OTf) and [(C,C,C)Pd-(CO)](OTf) with (allyl)MgBr and nBuLi led to the formation of zwitterionic phosphonium organopalladates [

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Section: Resultsmentioning

confidence: 99%

Direct Access to Palladium(II) Complexes Based on AnionicC,C,C-Phosphonium Ylide Core Pincer Ligand

et al. 2021

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“…An "ate complex" derived from n-BuLi addition to platinum has been considered, but this has little precedent. 30 Nucleophilic aromatic substitutions involving fluoroarenes have abundant precedent, but species derived from addition are only rarely observable 31 and our 19 F{ 1 H} spectra (Figure s2) show only sp 2 CF signals. 32 The formation of the byproduct PtH in so many of the preceding reactions also poses a puzzle.…”

Section: Synthesesmentioning

confidence: 77%

“…However, since the literature data are derived from 18-valence-electon octahedral complexes, it may not be unreasonable that resonances associated with 16-valence-electron square planar PtC 4 Li are among the slightly upfield group of signals at 17.7–17.1 ppm. An “ate complex” derived from n -BuLi addition to platinum has been considered, but this has little precedent . Nucleophilic aromatic substitutions involving fluoroarenes have abundant precedent, but species derived from addition are only rarely observable and our 19 F{ 1 H} spectra (Figure s2) show only sp 2 CF signals…”

Section: Discussionmentioning

confidence: 99%

Reactions of Platinum Terminal Polyynyl Complexes trans-(C₆F₅)(p-tol₃P)₂Pt(C≡C)_nH (n = 2–4) and n-BuLi, Generation of Functional Equivalents of Pt(C≡C)_nLi Species, and Derivatization with Organic and Inorganic Electrophiles

Dey Baksi,

Aggrey,

Bhuvanesh

et al. 2024

Organometallics

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Reactions of the title complexes and n-BuLi (1.5 equiv, −45 °C) afford functional equivalents of the deprotonated species trans-(C 6 F 5 )(p-tol 3 P) 2 Pt(C�C) n Li (n = 2−4), as assayed by subsequent additions of MeI or Me 3 SiCl to give trans-(C 6 F 5 )(ptol 3 P) 2 Pt(C�C) n Me (66−52%) or trans-(C 6 F 5 )(p-tol 3 P) 2 Pt(C� C) n SiMe 3 (63−49%). However, 31 P NMR data suggest more complicated mechanistic scenarios, and small amounts of the hydride complex trans-(C 6 F 5 )(p-tol 3 P) 2 PtH (independently synthesized from the chloride complex, AgClO 4 , and NaBH 4 ) are detected in most cases. Analogous sequences involving trans-(C 6 F 5 )(ptol 3 P) 2 Pt(C�C) 2 H and benzyl bromide, D 2 O, or W(CO) 6 /Me 3 O + BF 4− similarly afford products with Pt(C�C) 2 Bn, Pt(C�C) 2 D, or Pt(C�C) 2 C(OCH 3 )�W(CO) 5 linkages. The crystal structures of the tungsten and corresponding SiMe 3 adduct, the three Pt(C� C) n Me species, and hydride complex are determined.

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2,2′-Diphosphino- and 2,2′-Diarsenotolanes and Their Fe-, Co-, and Ni-Complexes: Pnictogen-Dependent Cyclization Tendencies and Metal-Dependent Stability and Reactivity Patterns

2023

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Common iron(II), cobalt(II), and nickel(II) bromides were reacted with 2,2′-bis(diisopropylphosphino)tolane 1-P (R = i Pr), which led to the isolation of P-heterocyclic chelate complexes (2-M, M = Fe, Co, and Ni) containing a new C−P and a new C−M bond. Attempts to reduce complexes 2-M (M = Fe, Co, and Ni), however, were unsuccessful, that is, no C−C coupling was observed, while diphosphadibenzo[a,e]pentalene formation was noticed in the majority of our experiments. To suppress the latter reactivity pattern, the reduced stability of As-ylides (in comparison to P-ylides) was exploited by preparing the arsaderivative of the ligand (1-As, R = i Pr), which was found to resist diarsadibenzo[a,e]pentalene formation. The lower tendency of 1-As to cyclize is also reflected in its reactions with MBr 2 (M = Fe, Co, and Ni). For M = Co, a κ 2 -As,As-coordinated complex (3-Co) with an uncoordinated alkyne backbone was obtained, while pincer formation was found to occur for M = Fe (3-Fe). Only in the case of nickel, an As-heterocyclic species (3-Ni) akin to 2-Ni was isolated. Upon reduction of 3-Ni, a trimetallic metallacyclopentadiene (4-Ni) was produced via alkyne C−C coupling, inferring that 3-Ni is prone to ring-opening under reducing conditions. Reduction of 3-Co was only successful in the presence of CO (2.5 atm), which led to the formation of a new As−C bond and the isolation of an As-heterocyclic cobalt tricarbonyl complex (5-Co). For 3-Fe, neither intermolecular C−C nor intramolecular As−C coupling was observed, but an unusual mixed-valent dimer with an [Fe 2 (alkyne) 2 ] + core (4-Fe) was generated and isolated upon reduction with Zn powder. Compounds 4-M (M = Ni and Fe) are discussed in the context of alkyne cycloadditions, given that related motifs have been proposed as key intermediates in these transformations.

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Properties and Reactivities of Zwitterionic Platinum(II)-ate Complexes Generated by Transforming Coordination of an Alkyne–Bisphosphine Ligand

Cited by 3 publications

References 48 publications

Direct Access to Palladium(II) Complexes Based on AnionicC,C,C-Phosphonium Ylide Core Pincer Ligand

Direct Access to Palladium(II) Complexes Based on AnionicC,C,C-Phosphonium Ylide Core Pincer Ligand

Reactions of Platinum Terminal Polyynyl Complexes trans-(C₆F₅)(p-tol₃P)₂Pt(C≡C)_nH (n = 2–4) and n-BuLi, Generation of Functional Equivalents of Pt(C≡C)_nLi Species, and Derivatization with Organic and Inorganic Electrophiles

2,2′-Diphosphino- and 2,2′-Diarsenotolanes and Their Fe-, Co-, and Ni-Complexes: Pnictogen-Dependent Cyclization Tendencies and Metal-Dependent Stability and Reactivity Patterns

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Properties and Reactivities of Zwitterionic Platinum(II)-ate Complexes Generated by Transforming Coordination of an Alkyne–Bisphosphine Ligand

Cited by 3 publications

References 48 publications

Direct Access to Palladium(II) Complexes Based on AnionicC,C,C-Phosphonium Ylide Core Pincer Ligand

Direct Access to Palladium(II) Complexes Based on AnionicC,C,C-Phosphonium Ylide Core Pincer Ligand

Reactions of Platinum Terminal Polyynyl Complexes trans-(C6F5)(p-tol3P)2Pt(C≡C)nH (n = 2–4) and n-BuLi, Generation of Functional Equivalents of Pt(C≡C)nLi Species, and Derivatization with Organic and Inorganic Electrophiles

2,2′-Diphosphino- and 2,2′-Diarsenotolanes and Their Fe-, Co-, and Ni-Complexes: Pnictogen-Dependent Cyclization Tendencies and Metal-Dependent Stability and Reactivity Patterns

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Reactions of Platinum Terminal Polyynyl Complexes trans-(C₆F₅)(p-tol₃P)₂Pt(C≡C)_nH (n = 2–4) and n-BuLi, Generation of Functional Equivalents of Pt(C≡C)_nLi Species, and Derivatization with Organic and Inorganic Electrophiles