286433-36-1Relevant academic research and scientific papers
d8 Nickel and palladium difluorocarbenes derived from trifluoromethyl POCOP-type pincer complexes
Lee, Graham M.,Korobkov, Ilia,Baker, R. Tom
, p. 270 - 277 (2017)
In this study, trifluoromethyl POCOP-type pincer complexes (iPrPOCOP)Ni(CF3) (1-CF3) and (iPrPOCOP)Pd(CF3) (2-CF3) are prepared. These complexes undergo Lewis acid-mediated fluoride abstraction to furnish cation
Activation of small molecules by a rhodium bis(phosphinite) pincer complex
Polezhaev,Kuklin,Ivanov,Petrovskii,Dolgushin,Ezernitskaya,Koridze
, p. 1847 - 1854 (2009)
Rhodium hydrido chloride pincer complex RhH(Cl)[2,6-(But 2PO)2C6H3] was synthesized and used for the preparation of new complexes with labile two-electron ligands Rh(L)[2,6-(But2
Practical Gas Cylinder-Free Preparations of Important Transition Metal-Based Precatalysts Requiring Gaseous Reagents
Ahrens, Alexander,Donslund, Bjarke S.,Gausas, Laurynas,Kristensen, Steffan K.,Skrydstrup, Troels,Sun, Hongwei
supporting information, p. 2300 - 2307 (2021/09/28)
A simple and safe setup for the synthesis of a selection of important transition metal-based precatalysts is reported, all requiring low-molecular weight gaseous reagents for their preparation. Hydrogen, carbon monoxide, ethylene, and acetylene are each liberated in a controlled manner from a corresponding easy-to-handle precursor in a closed two-chamber reactor. Gas cylinders and elaborate setups/techniques connected to handling toxic and/or flammable gases as reported in the literature can thus be avoided. The corresponding precatalysts are of high relevance in the active research fields of C-H bond activation, dehydrogenation, hydrogenation, and coupling reactions. The selection of complexes shown is meant to serve as examples for the usefulness and broadness of the presented methods, allowing precatalysts requiring gaseous reagents to become available for the research community.
Dinitrogen Reduction to Ammonium at Rhenium Utilizing Light and Proton-Coupled Electron Transfer
Bruch, Quinton J.,Connor, Gannon P.,Chen, Chun-Hsing,Holland, Patrick L.,Mayer, James M.,Hasanayn, Faraj,Miller, Alexander J. M.
supporting information, p. 20198 - 20208 (2019/12/24)
The direct scission of the triple bond of dinitrogen (N2) by a metal complex is an alluring entry point into the transformation of N2 to ammonia (NH3) in molecular catalysis. Reported herein is a pincer-ligated rhenium system that reduces N2 to NH3 via a well-defined reaction sequence involving reductive formation of a bridging N2 complex, photolytic N2 splitting, and proton-coupled electron transfer (PCET) reduction of the metal-nitride bond. The new complex (PONOP)ReCl3 (PONOP = 2,6-bis(diisopropylphosphinito)pyridine) is reduced under N2 to afford the trans,trans-isomer of the bimetallic complex [(PONOP)ReCl2]2(μ-N2) as an isolable kinetic product that isomerizes sequentially upon heating into the trans,cis and cis,cis isomers. All isomers are inert to thermal N2 scission, and the trans,trans-isomer is also inert to photolytic N2 cleavage. In striking contrast, illumination of the trans,cis and cis,cis-isomers with blue light (405 nm) affords the octahedral nitride complex cis-(PONOP)Re(N)Cl2 in 47% spectroscopic yield and 11% quantum yield. The photon energy drives an N2 splitting reaction that is thermodynamically unfavorable under standard conditions, producing a nitrido complex that reacts with SmI2/H2O to produce a rhenium tetrahydride complex (38% yield) and furnish ammonia in 74% yield.
High-Turnover Aromatic C-H Borylation Catalyzed by POCOP-Type Pincer Complexes of Iridium
Press, Loren P.,Kosanovich, Alex J.,McCulloch, Billy J.,Ozerov, Oleg V.
supporting information, p. 9487 - 9497 (2016/08/12)
The catalytic C-H borylation of arenes with HBpin (pin = pinacolate) using POCOP-type pincer complexes of Ir has been demonstrated, with turnover numbers exceeding 10 000 in some cases. The selectivity of C-H activation was based on steric preferences and largely mirrored that found in other Ir borylation catalysts. Catalysis in the (POCOP)Ir system depends on the presence of stoichiometric quantities of sacrificial olefin, which is hydrogenated to consume the H2 equivalents generated in the borylation of C-H bonds with HBpin. Smaller olefins such as ethylene or 1-hexene were more advantageous to catalysis than sterically encumbered tert-butylethylene (TBE). Olefin hydroboration is a competing side reaction. The synthesis and isolation of multiple complexes potentially relevant to catalysis permitted examination of several key elementary reactions. These experiments indicate that the C-H activation step in catalysis ostensibly involves oxidative addition of an aromatic C-H bond to the three-coordinate (POCOP)Ir species. The olefin is mechanistically critical to gain access to this 14-electron, monovalent Ir intermediate. C-H activation at Ir(I) here is in contrast to the olefin-free catalysis with state-of-the-art Ir complexes supported by neutral bidentate ligands, where the C-H activating step is understood to involve trivalent Ir-boryl intermediates.
POCOP-Type Pincer Complexes of Nickel: Synthesis, Characterization, and Ligand Exchange Reactivities of New Cationic Acetonitrile Adducts
Lapointe, Sbastien,Vabre, Boris,Zargarian, Davit
, p. 3520 - 3531 (2015/08/06)
This report describes the synthesis, characterization, and ligand exchange studies of a family of cationic acetonitrile adducts of nickel featuring resorcinol-based, pincer-type POCOP ligands. The compounds [(R-POCOPR′)Ni(NCMe)][OSO2CF3] (R-POCOPR′ = 2,6-(R′2PO)2(RnC6H3-n); R′ = i-Pr: R = H (1), p-Me (2), p-OMe (3), p-CO2Me (4), p-Br (5), m,m-t-Bu2 (6), m-OMe (7), m-CO2Me (8); R′ = t-Bu: R = H (9), p-CO2Me (10)) were prepared in 80-93% yields by reacting the corresponding charge-neutral bromo derivatives with Ag(OSO2CF3) in acetonitrile. The impact of the R- and R′-substituents on electronics and structures of 1-10 have been probed by NMR, UV-vis, and IR spectra, X-ray crystallography, and cyclic voltammetry measurements. The observed ν(C≡N) values were found to increase with the increasing electron-withdrawing nature of R, i.e., in the order 7 2C-substituted cations showed the highest oxidation potentials. Moreover, all cationic adducts showed greater oxidation potentials compared with their corresponding charge-neutral bromo precursors. Equilibrium studies conducted with selected [(R-POCOPR′)Ni(NCMe)][OSO2CF3] and (R-POCOPR′)NiBr (R′ = i-Pr) have confirmed facile MeCN/Br exchange between these derivatives and show that the cationic adducts are stabilized with MeO-POCOP, whereas the charge-neutral bromo species are stabilized with MeO2C-POCOP. The potential implications of these findings for the catalytic reactivities of the title cationic complexes have been discussed. (Chemical Equation Presented).
