94725-71-0Relevant articles and documents
Aerobic oxidation-functionalization of the aryl moiety in van Koten's pincer complex (NCN)Ni(ii)Br: Relevance to carbon-heteroatom coupling reactions promoted by high-valent nickel species
Cloutier, Jean-Philippe,Zamani, Fahimeh,Zargarian, Davit
, p. 1800 - 1807 (2022/01/31)
The growing popularity of metal-promoted C-H functionalization methodologies has led to increased efforts aimed at improving our understanding of the mechanistic underpinnings of C-C and C-heteroatom bond forming steps. One approach to such mechanistic studies involves probing the reactivities of model complexes featuring chelate-stabilized M-hydrocarbyl moieties. The present study uses van Koten's (NCN)Ni(ii)Br compound as a model for probing C-heteroatom coupling with protic substrates HX (X = NHR, OR). Our results establish the crucial importance of aerobic (oxidative) conditions for promoting reactivities that give the functionalized ligands NC(X)N. The importance of oxidation for the C-heteroatom bond formation is further deduced from the reaction of the structurally authenticated complex (NCN)Ni(OSiMe3) with CuBr2 to give the C-O functionalization product NC(OSiMe3)N. This journal is
C-O and C-N Functionalization of Cationic, NCN-Type Pincer Complexes of Trivalent Nickel: Mechanism, Selectivity, and Kinetic Isotope Effect
Cloutier, Jean-Philippe,Rechignat, Lionel,Canac, Yves,Ess, Daniel H.,Zargarian, Davit
supporting information, p. 3861 - 3874 (2019/04/05)
This report presents the synthesis of new mono- and dicationic NCN-NiIII complexes and describes their reactivities with protic substrates. (NCN is the pincer-type ligand κN, κC, κN-2,6-(CH2NMe2)2-C6H3.) Treating van Koten's trivalent complex (NCN)NiIIIBr2 with AgSbF6 in acetonitrile gives the dicationic complex [(NCN)NiIII(MeCN)3]2+, whereas the latter complex undergoes a ligand-exchange reaction with (NCN)NiIIIBr2 to furnish the related monocationic complex [(NCN)NiIII(Br)(MeCN)]+. These trivalent complexes have been characterized by X-ray diffraction analysis and EPR spectroscopy. Treating these trivalent complexes with methanol and methylamine led, respectively, to C-OCH3 or C-NH(CH3) functionalization of the Ni-aryl moiety in these complexes, C-heteroatom bond formation taking place at the ipso-C. These reactions also generate the cationic divalent complex [(NCN)NiII(NCMe)]+, which was prepared independently and characterized fully. The unanticipated formation of the latter divalent species suggested a comproportionation side reaction between the cationic trivalent precursors and a monovalent species generated at the C-O and C-N bond formation steps; this scenario was supported by direct reaction of the trivalent complexes with the monovalent compound (PPh3)3NiICl. Kinetic measurements and density functional theory analysis have been used to investigate the mechanism of these C-O and C-N functionalization reactions and to rationalize the observed inverse kinetic isotope effect in the reaction of [(NCN)NiIII(Br)(MeCN)]+ with CH3OH/CD3OD.
Functionalization of the Aryl Moiety in the Pincer Complex (NCN)NiIIIBr2: Insights on NiIII-Promoted Carbon-Heteroatom Coupling
Cloutier, Jean-Philippe,Zargarian, Davit
, p. 1446 - 1455 (2018/05/23)
This report describes the C-O, C-N, and C-halogen functionalization of the NiIII-Ar moiety stabilized within a pincer framework that serves as a model system for studying C-heteroatom coupling reactions promoted by high-valent Ni compounds. Treating van Koten's pincer complex (NCN)NiIIIBr2 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 a comproportionation reaction between the trivalent precursor and a NiI 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 NH3. Kinetic measurements have established that the reaction with MeOH is first-order with respect to [(NCN)NiIIIBr2], and a kinetic isotope effect of 0.47 has been obtained for functionalization with CH3OH/CD3OD. 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)NiIVBr2]+ 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.
Inclusion Compounds of Organic Onium Salts, IV. Organyl Ammonium Hosts as Versatile Clathrate Formers
Loehr, Hans-Gerd,Josel, Hans-Peter,Engel, Aloys,Voegtle, Fritz,Schuh, Willy,Puff, Heinrich
, p. 1487 - 1496 (2007/10/02)
The organyl-oligo-ammonium compounds 1 - 25 and their clathrates with a variety of low molecular weight neutral compounds, especially solvent molecules, are prepared.The inclusion capacity of the new clathrands can be explained by interstices in the host lattice.The conformational flexibility of the voluminous onium branches is responsible for the great number of clathrates; their stability depends on the ion lattice.The X-ray analysis of the ethanol clathrate of the onium host 8 shows that one ethanol molecule is surrounded by the host molecules in a cage-type manner.The great variety of the inclusions obtained up to now demonstrates that the oligo onium host compounds have to be considered as the most universal clathrands of organic chemistry.Hints are given for the syntheses of new onium clathrates.
