Convenient preparation of (η4-alkadiene)dichloroplatinum(II) complexes from [PtCl6]2− anions and their reduction to platinum(0) alkene complexes under phase-transfer catalysis conditions

Dell’Amico, Daniela Belli; Labella, Luca; Marchetti, Fabio; Samaritani, Simona

doi:10.1016/j.jorganchem.2010.12.043

Cited by 16 publications

(10 citation statements)

References 53 publications

(18 reference statements)

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“…The complexes [M(κ 2 -2-C 6 F 4 PPh 2 ) 2 ] (M = Pt, Pd), [Pt(PPh 3 ) 3 ], [Pd(PPh 3 ) 4 ], [Pd(AsPh 3 ) 4 ], and [Pd(η 5 -Cp)(η 3 -allyl)] were prepared by literature methods. [Pt 3 (CN t Bu) 6 ] was prepared by a reported method using [Pt(norbornene) 3 ] , instead of [Pt(1,5-cyclooctadiene) 2 ]; all other reagents were commercially available and used as received. 1 H (300 MHz), 19 F (282 MHz), and 31 P (121 MHz) NMR spectra were measured as C 6 D 6 solutions, unless otherwise stated, on a Bruker Avance 300 spectrometer at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C₆F₄PPh₂: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

et al. 2012

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Comproportionation of trans-[Pd(κ 2-2-C 6 F 4 PPh 2) 2 ] with [PdL 4 ] (L = PPh 3 , AsPh 3) gives metal− metal-bonded dipalladium(I) complexes [Pd 2 I (μ-2-C 6 F 4 PPh 2) 2 (L) 2 ] [L = PPh 3 (5), AsPh 3 (6)] in which the bridging ligands adopt a head-to-tail arrangement. The corresponding diplatinum(I) complex [Pt 2 I (μ-2-C 6 F 4 PPh 2) 2 (PPh 3) 2 ] (9) is obtained similarly from [Pt(κ 2-2-C 6 F 4 PPh 2) 2 ] and [Pt(PPh 3) 3 ]. The separations between the metal atoms in the dipalladium(I) complexes [2.5740(3) Å (5), 2.5511(3) Å (6)] are slightly less than that in the diplatinum(I) complex 9 [2.61179(15) Å]. The axial triphenylarsine ligands of 6 are replaced by tert-butyl isocyanide to give the dipalladium(I) complex [Pd 2 I (μ-2-C 6 F 4 PPh 2) 2 (CN t Bu) 2 ] (7). However, treatment of trans-[Pd(κ 2-2-C 6 F 4 PPh 2) 2 ] with [Pd(CN t Bu) 2 ], generated in situ from a mixture of tert-butyl isocyanide and [Pd(η 5-Cp)(η 3-allyl)], gives a formally mixed-valent palladium(0)−palladium(II) complex [Pd 2 0/II (μ-2-C 6 F 4 PPh 2) 2 (CN t Bu) 2 ] (8), in which the bridging ligands are arranged head-to-head. In contrast, comproportionation of [Pt(κ 2-2-C 6 F 4 PPh 2) 2 ] with [Pt 3 (CN t Bu) 6 ] gives the diplatinum(I) complex [Pt 2 I (μ-2-C 6 F 4 PPh 2) 2 (CN t Bu) 2 ] (10) analogous to 7; there was no evidence for the formation of a dinuclear mixed-valent species. Although complexes 7 and 8 are isomers, with similar Pd−Pd separations [2.5803(4) Å (7), 2.5580(2) Å (8)], they do not interconvert in solution. The diplatinum(I) complex 9 undergoes oxidative addition with iodine to give an A-frame cation, [Pt 2 (μ-I)(μ-2-C 6 F 4 PPh 2) 2 (PPh 3) 2 ] + , isolated as its PF 6 − salt (11). In contrast, the dipalladium(I) complex 5 eliminates one of the PPh 3 ligands when it undergoes oxidative addition with halogens and with methyl iodide, the products being A-frame dipalladium(II) complexes [Pd 2 X(μ-Y)(μ-2-C 6 F 4 PPh 2) 2 (PPh 3)] [X = Y = I (12), Cl (13); X = Me, Y = I (14)]. The metal−metal distances in 11−14 [2.9478(5) Å (11), 2.8078(7) Å (12), 2.8241(3) Å (13), and 2.8013(5) Å (14)] are ca. 0.3 Å greater than in their dimetal(I) precursors, consistent with a weaker metal−metal interaction in the dimetal(II) complexes. Unexpectedly, reaction of 5 with iodobenzene gives a mononuclear palladium(II) complex, cis-[Pd(κ 2 C,P-2-C 6 F 4 PPh 2)(κC-2-C 6 F 4 PPh 2)(PPh 3)] (15). This is suggested to be formed by a sequence of (a) oxidative addition of iodobenzene to 5 to give a σ-phenyl complex analogous to the σ-methyl complex 14, (b) a change in the binding mode of one of the 2-C 6 F 4 PPh 2 ligands from μto κ 2-, and (c) reductive elimination of tetraphenylphosphonium iodide and loss of Pd(0).

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Section: Methodsmentioning

confidence: 99%

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C₆F₄PPh₂: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

et al. 2012

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“…Addition of ligands (L) such as phosphines (monodentate or bidentate) or bipyridyls10 give complexes of the type [Pd 0 (η 2 ‐dba)(L) 2 ]. The platinum variant, [Pt 0 2 (dba‐H) 3 ], is also known 11…”

Section: Introductionmentioning

confidence: 99%

A Remarkable cis‐ and trans‐Spanning Dibenzylidene Acetone Diphosphine Chelating Ligand (dbaphos)

Jarvis

Sehnal

Bajwa

et al. 2013

Chemistry A European J

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A multidentate and flexible diolefin-diphosphine ligand, based on the dibenzylidene acetone core, namely dbaphos (1), is reported herein. The ligand adopts an array of different geometries at Pt, Pd and Rh. At Pt(II) the dbaphos ligand forms cis- and trans-diphosphine complexes and can be defined as a wide-angle spanning ligand. (1)H NMR spectroscopic analysis shows that the β-hydrogen of one olefin moiety interacts with the Pt(II) centre (an anagostic interaction), which is supported by DFT calculations. At Pd(0) and Rh(I), the dbaphos ligand exhibits both olefin and phosphine interactions with the metal centres. The Pd(0) complex of dbaphos is dinuclear, with bridging diphosphines. The complex exhibits the coordination of one olefin moiety, which is in dynamic exchange (intramolecular) with the other "free" olefin. The Pd(0) complex of dbaphos reacts with iodobenzene to afford trans-[Pd(II)(dbaphos)I(Ph)]. In the case of Rh(I), dbaphos coordinates to form a structure in which the phosphine and olefin moieties occupy both axial and equatorial sites, which stands in contrast to a related bidentate olefin, phosphine ligand ("Lei" ligand), in which the olefins occupy the equatorial sites and phosphines the axial sites, exclusively.

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“…Under the optimal reaction conditions, a series of kinetic studies were conducted (Scheme 6). Interestingly, the progress curve of the reaction initiated with Pt(cod) 2 (Supporting Information Figure S1), a highly efficient precursor for the generation of Pt(0) species, 55 was completely different from the curve of the reaction that was initiated with Pt(cod)Me 2 . The reaction starting with Pt(cod)Me 2 had a pronounced induction period (>30 min), and the reaction rate was much slower than that of the reaction initiated with Pt(cod) 2 .…”

Section: Studies Toward the Reaction Mechanism And Origins Of Selectivitiesmentioning

confidence: 88%

Platinum-Catalyzed Allylic C–H Alkylation with Malononitriles

et al. 2022

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The direct functionalization of allylic C-H bonds is distinguished by enabling rapid assembly of structural complexity from simple molecules. Although Pd-catalyzed allylic C-H functionalization has been extensively studied, the discovery of new catalytic systems remains fairly underdeveloped. Here, we disclose a Pt-catalyzed allylic C-H alkylation of a wide range of α-alkenes by using phosphoramidites as ligands and malononitriles as alkylating reagents. Notably, the combination of chiral ureacatalyzed Michael addition and Pt-catalyzed allylic C-H alkylation can serve as an efficient protocol to access chiral tetrahydropyran with high levels of diastereo-and enantioselectivity. Mechanistic studies suggest that the Pt-catalyzed allylic C-H activation proceeds through a concerted proton and two-electron transfer process, which is analogous to transition state geometries of Pd catalysis.

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Convenient preparation of (η4-alkadiene)dichloroplatinum(II) complexes from [PtCl6]2− anions and their reduction to platinum(0) alkene complexes under phase-transfer catalysis conditions

Cited by 16 publications

References 53 publications

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C₆F₄PPh₂: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C₆F₄PPh₂: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

A Remarkable cis‐ and trans‐Spanning Dibenzylidene Acetone Diphosphine Chelating Ligand (dbaphos)

Platinum-Catalyzed Allylic C–H Alkylation with Malononitriles

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Convenient preparation of (η4-alkadiene)dichloroplatinum(II) complexes from [PtCl6]2− anions and their reduction to platinum(0) alkene complexes under phase-transfer catalysis conditions

Cited by 16 publications

References 53 publications

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C6F4PPh2: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C6F4PPh2: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

A Remarkable cis‐ and trans‐Spanning Dibenzylidene Acetone Diphosphine Chelating Ligand (dbaphos)

Platinum-Catalyzed Allylic C–H Alkylation with Malononitriles

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Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C₆F₄PPh₂: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species

Preparation, Structure, and Reactivity of Dipalladium(I) Complexes Containing the Carbanion 2-C₆F₄PPh₂: Coexistence of Distinct, Noninterconverting Head-to-Head [Dipalladium(0/II)] and Head-to-Tail [Dipalladium(I)] Species