Organonickel(II) complexes with anionic tridentate 1, 3-bis(azolylmethyl)phenyl ligands. synthesis, structural characterization and catalytic behavior

Abstract

A reação de 2-bromo-1,3-bis(bromometil)benzeno com 3,5-dimetilpirazol e 1H-indazol produz os ligantes tridentados 2-bromo-1,3-bis(3,5-dimetilpirazol-1-ilmetil)benzeno (1) e 2-bromo-1,3-bis(indazol-2-ilmetil)benzeno (2). Estes compostos reagem com [Ni(cod) 2 ] em tetraidrofurano (thf) para formar os complexos de adição oxidativa [NiBr{1,3-bis(azolilmetil)fenil-N,C,N}], azol = 3,5-dimetilpirazol (3) e indazol (4), os quais foram isolados em bons rendimentos como sólidos amarelos estáveis e caracterizados por meio de análise elementar, espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR), espectrometria de massa e ressonância magnética nuclear (NMR). Adicionalmente, as estruturas moleculares de 2 e 4 foram determinadas por difratometria de raios X de monocristal. O complexo 4 foi testado como catalisador na reação de polimerização de etileno.The reaction of 2-bromo-1,3-bis(bromomethyl)benzene with 3,5-dimethylpyrazole and 1H-indazole yields the tridentate ligands 2-bromo-1,3-bis(3,5-dimethylpirazol-1-ylmethyl)benzene (1) and 2-bromo-1,3-bis(indazol-2-ylmethyl)benzene (2). These compounds react with [Ni(cod) 2 ] in tetrahydrofuran (thf) to form the oxidative addition complexes [NiBr{1,3-bis(azolylmethyl)phenyl-N,C,N}], azol = 3,5-dimethylpyrazol (3), indazol (4), which were isolated in good yields as stable yellow solids and characterized by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), mass spectroscopy and nuclear magnetic resonance (NMR). In addition, the molecular structures of 2 and 4 were determined by single-crystal X-ray diffraction analysis. Complex 4 was tested as a catalyst in ethylene polymerization reaction.

Fluoro and Trifluoromethyl Derivatives of POCOP-Type Pincer Complexes of Nickel: Preparation and Reactivities in SN2 Fluorination and Direct Benzylation of Unactivated Arenes

“…Finally, there are even fewer pincer-type analogues of these complexes. Thus, the first fluoride derivative of a pincer complex of nickel, (PCP t-Bu )NiF, was reported in 2011 by Peruzzini's group, 31 and Caḿpora's group reported the analogous PCP i-Pr complex in 2012; 24 This paucity of data on (pincer)NiF and (pincer)NiCF 3 species is somewhat surprising given the practical importance of fluorination methodologies and the documented reactivities of pincer-Ni complexes in diverse catalytic transformations, including: cyanomethylation, 33 hydrosilylation, 34 CO 2 reduction; 35 Kumada, 36 Suzuki−Miyaura, 37 and Mizoroki−Heck coupling; 38 Zn-mediated homocoupling; 39 electrocatalytic hydrogen production; 40 ethylene polymerization, 41 Michaeltype hydroamination, 42 hydroalkoxylation 42b,c,43 and C−C bond formation; 38,44 and Kharasch addition. 42a,45 The intense interest in pincer complexes of nickel is also due to their ease of synthesis, enhanced thermal stabilities and diverse reactivities compared to analogous complexes based on nonchelating ligands, and the relative abundance of nickel.…”

“…This paucity of data on (pincer)NiF and (pincer)NiCF 3 species is somewhat surprising given the practical importance of fluorination methodologies and the documented reactivities of pincer-Ni complexes in diverse catalytic transformations, including: cyanomethylation, hydrosilylation, CO 2 reduction; Kumada, Suzuki–Miyaura, and Mizoroki–Heck coupling; Zn-mediated homocoupling; electrocatalytic hydrogen production; ethylene polymerization, Michael-type hydroamination, hydroalkoxylation ,, and C–C bond formation; , and Kharasch addition. , The intense interest in pincer complexes of nickel is also due to their ease of synthesis, enhanced thermal stabilities and diverse reactivities compared to analogous complexes based on nonchelating ligands, and the relative abundance of nickel . The above considerations and our interest in the reactivities of pincer-type nickel complexes prompted us to prepare fluoro and trifluoromethyl derivatives of these complexes and explore their reactivities.…”

Palladium Complex Bearing 3,5-Bis(benzotriazol-1-Ylmethyl)toluene Ligand Catalyzes Oxidative Amination of Allyl Butyl Ether

“…[17][18][19][20][21][22] Recently, we described the synthesis of new palladium complexes bearing the bidentate 3,5-bis(azol-1-ylmethyl)toluene ligands (azol = 3,5-dimethylpyrazol, indazol), which in the presence of methylaluminoxane lead to active catalysts for the polymerization of ethylene. 23 The palladium(II) complex containing 3,5-bis(indazol-1-ylmethyl)toluene is active as catalysts in C-C coupling reactions involving aryl halides substrates.…”

“…23 The palladium(II) complex containing 3,5-bis(indazol-1-ylmethyl)toluene is active as catalysts in C-C coupling reactions involving aryl halides substrates. 24 On the other hand, a variety of palladium(II) complexes have been successfully studied as catalysts for the aerobic oxidative amination of unactivated alkenes to yield amine derivatives. [25][26][27][28][29][30][31][32][33][34][35][36][37][38] This catalytic reaction leads to the formation of imines or enamines, via b-hydride elimination, through a mechanism analogous to the well-known Wacker process.…”