Dicyclometalated Mononuclear Bis(carbene)platinum(IV) Complexes

Zhang, Shiwei; Takahashi, Shigetoshi

doi:10.1021/om9805077

Cited by 18 publications

(11 citation statements)

References 35 publications

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“…Platinum(II) complexes of N-heterocyclic carbenes (NHC) have attracted considerable attention during the last years, especially complexes with chelating bis(NHC) ligands, which show an increased stability against oxidizing and acidic media, therefore tolerating harsher reaction conditions compared to catalysts with phosphine ligands. − In contrast, only a few examples for Pt(IV) carbene complexes − are known and even less for Pt(IV) NHC complexes − (Figure ). Pt(IV) complexes 1 , 2 (R 1 −R 4 = H, Me, Alkyl, Ph, COR, COOR) and 3a − c (X = NMe, O, S) with monodentate NHC ligands are prepared by ligand substitution from Pt(IV) precursors, − while the only examples with a chelating NHC ligand ( 4a , 4b ) have been synthesized by oxidative addition of methyl iodide or triflic acid .…”

Section: Introductionmentioning

confidence: 99%

Platinum(IV) Complexes with Chelating N-Heterocyclic Carbene Ligands

2010

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Platinum(II) complexes with one or two chelating bis(NHC) ligands have been oxidized by bromine as well as iodobenzene dichloride to provide the corresponding platinum(IV) carbene complexes in good yields under very mild reaction conditions. All compounds have been fully characterized by 1H and 13C NMR spectroscopy and in three cases also by solid-state structures. The NMR spectra of the novel Pt(IV) complexes show significantly shifted signals compared to their Pt(II) precursor complexes.

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Section: Introductionmentioning

confidence: 99%

Platinum(IV) Complexes with Chelating N-Heterocyclic Carbene Ligands

2010

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“…Nonheterocyclic carbenes can be synthesized by the reaction of a coordinated isonitrile with a nucleophile of the type Nu-H, in which proton transfer from the nucleophile to the nitrogen of the isonitrile occurs (eq ). Platinum carbene complexes derived from platinum isonitrile complexes are dominated by Pt(0) and Pt(II) compounds, while platinum(IV) carbene complexes remain rare. − …”

Section: Introductionmentioning

confidence: 99%

Synthesis of Isonitrile, Iminoacyl, and Aminocarbene Tp′Pt Complexes

2010

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Generation of a reactive Tp′PtMe fragment (Tp′ = hydridotris(3,5-dimethylpyrazolyl)borate) in the presence of free isonitrile leads to a σ-isocyanide Pt(II) complex. Related Pt(II) aminocarbene complexes can be synthesized by nucleophilic attack at the isonitrile carbon followed by addition of acid. Protonation at nitrogen produces the observed aminocarbene product. Nucleophilic attack at the carbon of the coordinated isonitrile by metal alkyl reagents followed by addition of iodomethane as an electrophilic reagent results in Pt(IV) iminoacyl complexes of the type Tp′Pt(RCN(2,6-C6Me2H3))Me2, where R = Me, Et. Alternatively, the Pt(II) aminocarbene complexes can be converted to these same Pt(IV) iminoacyl products by deprotonation of the N−H site followed by addition of iodomethane, with the outcome reflecting methylation at platinum. Addition of acid to the Pt(IV) iminoacyl complex generates a rare cationic Pt(IV) aminocarbene complex via protonation at the iminoacyl nitrogen as {Tp′Pt(C(R)NH(2,6-C6Me2H3))Me2}{BF4} forms.

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“…13 To date, the vast majority of cycloplatination reactions have involved starting with, and ending up with platinum(II) species, though other examples have platinum(IV) species being formed by oxidative addition to these platinum(II) complexes. [14][15][16][17] Such platinum(IV) species are proving to be of increasing interest, including use as sensors 18 and as models for the Fischer-Tropsch synthesis. 19 Even though the reductive elimination of hydrocarbons from platinum(IV), which can be seen as analogous to the reverse of a C-H activation, has been widely studied, 20-25 and the Pt(II)/Pt(IV) redox cycle has been investigated as a model for the activation of C-H bonds, 26, 27 there have been few reports of C-H activation by a platinum(IV) centre to date.…”

Section: Introductionmentioning

confidence: 99%

Cyclometallated platinum(ii) complexes: oxidation to, and C–H activation by, platinum(iv)

et al. 2007

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A series of cyclometallated phenylpyridine platinum(II) complexes have been synthesised with a systematic variation in both the phenylpyridine and the ancillary ligand. Oxidation of one of the cyclometallated species leads to a number of isomeric platinum(IV) complexes, all of which eventually isomerize to a single compound. The route to these new compounds has been demonstrated to involve an initial slow oxidation followed by a rapid C-H activation to give doubly cyclometallated complexes. The solid state structures of a number of both the platinum(II) and the platinum(IV) species have been solved; many of the structures exhibited extended interactions that result in complex three dimensional packing.

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Dicyclometalated Mononuclear Bis(carbene)platinum(IV) Complexes

Cited by 18 publications

References 35 publications

Platinum(IV) Complexes with Chelating N-Heterocyclic Carbene Ligands

Platinum(IV) Complexes with Chelating N-Heterocyclic Carbene Ligands

Synthesis of Isonitrile, Iminoacyl, and Aminocarbene Tp′Pt Complexes

Cyclometallated platinum(ii) complexes: oxidation to, and C–H activation by, platinum(iv)

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