Adduct Studies and Reactivity of trans-[(C2F5)2MeP]2Pt(Me)X (X = O2CCF3, OTF, OSO2F)

Butikofer, Jeffrey L.; Parson, Thomas G.; Roddick, Dean M.

doi:10.1021/om060847p

Cited by 15 publications

(7 citation statements)

References 46 publications

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“…The complex [PtH{PMe(C 2 F 5 ) 2 } 2 (CO)] + (not listed in the table) is likely to be extremely acidic because of the CO and fluorinated ligands. It is prepared in neat triflic acid …”

Section: Specific Observations According To the Groupmentioning

confidence: 97%

“…It is prepared in neat triflic acid. 298 The nickel(III) hydride [NiH(P t Bu 2 CH 2 C 6 H 3 CH 2 P t Bu 2 )] + is calculated to have a pK a MeCN 1.7 (entry 12). 299 .…”

Section: Other Complexesmentioning

confidence: 99%

“…295,296 See the catalysis section 6.8 for more details. 298 The nickel(III) hydride [NiH(P t Bu 2 CH 2 C 6 H 3 CH 2 P t Bu 2 )] + is calculated to have a pK a MeCN 1.7 (entry 12). 299 The cyclometalated aryl in this pincer complex makes the hydride less acidic than the dicationic nickel(III) hydrides discussed above.…”

Section: Monocationicmentioning

confidence: 99%

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Brønsted–Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

2016

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Transition metal hydride complexes are usually amphoteric, not only acting as hydride donors, but also as Brønsted-Lowry acids. A simple additive ligand acidity constant equation (LAC for short) allows the estimation of the acid dissociation constant Ka(LAC) of diamagnetic transition metal hydride and dihydrogen complexes. It is remarkably successful in systematizing diverse reports of over 450 reactions of acids with metal complexes and bases with metal hydrides and dihydrogen complexes, including catalytic cycles where these reactions are proposed or observed. There are links between pKa(LAC) and pKa(THF), pKa(DCM), pKa(MeCN) for neutral and cationic acids. For the groups from chromium to nickel, tables are provided that order the acidity of metal hydride and dihydrogen complexes from most acidic (pKa(LAC) -18) to least acidic (pKa(LAC) 50). Figures are constructed showing metal acids above the solvent pKa scales and organic acids below to summarize a large amount of information. Acid-base features are analyzed for catalysts from chromium to gold for ionic hydrogenations, bifunctional catalysts for hydrogen oxidation and evolution electrocatalysis, H/D exchange, olefin hydrogenation and isomerization, hydrogenation of ketones, aldehydes, imines, and carbon dioxide, hydrogenases and their model complexes, and palladium catalysts with hydride intermediates.

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“…The complex [PtH{PMe(C 2 F 5 ) 2 } 2 (CO)] + (not listed in the table) is likely to be extremely acidic because of the CO and fluorinated ligands. It is prepared in neat triflic acid …”

Section: Specific Observations According To the Groupmentioning

confidence: 97%

“…It is prepared in neat triflic acid. 298 The nickel(III) hydride [NiH(P t Bu 2 CH 2 C 6 H 3 CH 2 P t Bu 2 )] + is calculated to have a pK a MeCN 1.7 (entry 12). 299 .…”

Section: Other Complexesmentioning

confidence: 99%

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Brønsted–Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

2016

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“…The proposed mechanism, involving three fundamental steps, is shown in Scheme : (1) CH activation of methane by Pt II species (proposed to be (H 2 O) 2 PtCl 2 ) to generate a Pt II –CH 3 intermediate, (2) oxidation of the Pt II –CH 3 intermediate by inorganic Pt IV to generate a Pt IV –CH 3 species, and (3) reductive functionalization of the Pt IV –CH 3 to generate the functionalized product CH 3 X (X = OH, Cl) and the Pt II catalyst. ,− Unfortunately, rigorous mechanistic investigation of the actual Shilov system is challenging due to the relative complexity of the system combined with interfering side reactions. As such, the reaction mechanism has been probed by several groups via simplified systems, designed to examine fundamental reactivity while avoiding the complexity associated with the original system. − …”

Section: Catalytic Systems That Utilize O2/o2-regenerable Oxidants An...mentioning

confidence: 99%

Homogeneous Functionalization of Methane

et al. 2017

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One of the remaining "grand challenges" in chemistry is the development of a next generation, less expensive, cleaner process that can allow the vast reserves of methane from natural gas to augment or replace oil as the source of fuels and chemicals. Homogeneous (gas/liquid) systems that convert methane to functionalized products with emphasis on reports after 1995 are reviewed. Gas/solid, bioinorganic, biological, and reaction systems that do not specifically involve methane functionalization are excluded. The various reports are grouped under the main element involved in the direct reactions with methane. Central to the review is classification of the various reports into 12 categories based on both practical considerations and the mechanisms of the elementary reactions with methane. Practical considerations are based on whether or not the system reported can directly or indirectly utilize O as the only net coreactant based only on thermodynamic potentials. Mechanistic classifications are based on whether the elementary reactions with methane proceed by chain or nonchain reactions and with stoichiometric reagents or catalytic species. The nonchain reactions are further classified as CH activation (CHA) or CH oxidation (CHO). The bases for these various classifications are defined. In particular, CHA reactions are defined as elementary reactions with methane that result in a discrete methyl intermediate where the formal oxidation state (FOS) on the carbon remains unchanged at -IV relative to that in methane. In contrast, CHO reactions are defined as elementary reactions with methane where the carbon atom of the product is oxidized and has a FOS less negative than -IV. This review reveals that the bulk of the work in the field is relatively evenly distributed across most of the various areas classified. However, a few areas are only marginally examined, or not examined at all. This review also shows that, while significant scientific progress has been made, greater advances, particularly in developing systems that can utilize O, will be required to develop a practical process that can replace the current energy and capital intensive natural gas conversion process. We believe that this classification scheme will provide the reader with a rapid way to identify systems of interest while providing a deeper appreciation and understanding, both practical and fundamental, of the extensive literature on methane functionalization. The hope is that this could accelerate progress toward meeting this "grand challenge."

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“…A similar case of such dual reactivity has been reported by Roddick for the reactions of trans-{PMe(C 2 F 5 ) 2 } 2 Pt(X)Me with different HX: HOTf leads to elimination of Me−H, i.e., protonolysis), whereas the more oxidizing acid HOSO 2 F generates Me-OSO 2 F, i.e., C−X coupling presumably via a Pt IV −Me intermediate (Scheme 7). 21 Ar−halide coupling observed with 2 is also reminiscent of the analogous reactivity reported for the Cu III complex shown in Scheme 7. 22 Protonation of the tertiary amine ligand moiety in this compound compromises its thermal stability and leads to C−halide bond formation.…”

Section: ■ Introductionmentioning

confidence: 99%

Functionalization of the Aryl Moiety in the Pincer Complex (NCN)Ni^IIIBr₂: Insights on Ni^III-Promoted Carbon–Heteroatom Coupling

Cloutier

Zargarian

2018

Organometallics

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This report describes the C−O, C−N, and C− halogen functionalization of the Ni III −Ar moiety stabilized within a pincer framework that serves as a model system for studying C−heteroatom coupling reactions promoted by highvalent Ni compounds. Treating van Koten's pincer complex (NCN)Ni III Br 2 under a nitrogen atmosphere with water, 1°or 2°alcohols, 1°amines, HCl, or HBr results in heterofunctionalization at the ipso-C of the pincer ligand's aryl moiety. The yields of these heterofunctionalizations are generally <50%, which has been attributed to the occurrence of a comproportionation reaction between the trivalent precursor and a Ni I species arising from the reductive elimination step in the functionalization process. Other side-reactions include a C−OH coupling with residual water and C−H coupling (net protonation) that is prevalent with mineral acids, some alcohols, and aqueous NH 3 . Kinetic measurements have established that the reaction with MeOH is first-order with respect to [(NCN)Ni III Br 2 ], and a kinetic isotope effect of 0.47 has been obtained for functionalization with CH 3 OH/CD 3 OD. These and other observations have allowed us to propose two different mechanistic postulates for the involvement of trivalent intermediates in the functionalization reactions under discussion. Tetravalent species such as [(NCN)Ni IV Br 2 ] + can be generated in situ under strongly oxidative conditions and they do promote C−Br coupling, but such species play no role in the C−heteroatom coupling reactions under nonoxidative conditions.

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Adduct Studies and Reactivity of trans-[(C₂F₅)₂MeP]₂Pt(Me)X (X = O₂CCF₃, OTF, OSO₂F)

Cited by 15 publications

References 46 publications

Brønsted–Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

Brønsted–Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

Homogeneous Functionalization of Methane

Functionalization of the Aryl Moiety in the Pincer Complex (NCN)Ni^IIIBr₂: Insights on Ni^III-Promoted Carbon–Heteroatom Coupling

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Adduct Studies and Reactivity of trans-[(C2F5)2MeP]2Pt(Me)X (X = O2CCF3, OTF, OSO2F)

Cited by 15 publications

References 46 publications

Brønsted–Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

Brønsted–Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

Homogeneous Functionalization of Methane

Functionalization of the Aryl Moiety in the Pincer Complex (NCN)NiIIIBr2: Insights on NiIII-Promoted Carbon–Heteroatom Coupling

Contact Info

Product

Resources

About

Adduct Studies and Reactivity of trans-[(C₂F₅)₂MeP]₂Pt(Me)X (X = O₂CCF₃, OTF, OSO₂F)

Functionalization of the Aryl Moiety in the Pincer Complex (NCN)Ni^IIIBr₂: Insights on Ni^III-Promoted Carbon–Heteroatom Coupling