A series of binuclear, divalent nickel and copper acetylacetonato complexes of the type [M(acac)-{µ-C 6 H 2 (dNAr) 4 }M(acac)] (M ) Ni, Cu) have been synthesized by reaction of the corresponding M(acac) 2 precursor with various bulky steric hindrace π-acceptor N-substituted 2,5-diamino-1,4-benzoquinonediimines C 6 H 2 (NHAr) 2 ()NAr) 2 (1a, Ar ) 4-C 6 H 4 Me; 1b, Ar ) 2-C 6 H 4 Me; 1c, Ar ) 2,6-C 6 H 3 Me 2 ), which are metalated and become bridging ligands. The ligands and complexes were determined by IR and UV-visible spectra and element analysis. Cyclic voltammetric behavior of complexes 2c and 3c has been tested. The molecular structures of the ligand 1c and the complexes [Ni(acac){µ-C 6 H 2 (dN(4-methyl-Ph)) 4 }Ni(acac)]) (2a), [Ni(acac){µ-C 6 H 2 (dN(2,6-dimethyl-Ph)) 4 }Ni(acac)]) (2c), and [Cu(acac)-{µ-6 H 2 (dN(2,6-dimethyl-Ph)) 4 }Cu(acac)]) (3c) have been determined by X-ray diffraction. The coordination geometry around the metal ions of the Ni and Cu complexes is square-planar, and a complete electronic delocalization of the quinonoid π-system occurs between the metal centers over the two NdC-CdCdN halves of the ligand. In the presence of MAO as cocatalyst, all the Ni complexes exhibited high activities both for addition polymerization of norbornene and for methyl methacrylate (MMA) polymerization, which produce syndiotactic-rich poly(methyl methacrylate) (PMMA) with broad molecular weight distribution; however, the Cu complexes show moderate activities for norbornene polymerization and are inactive for MMA polymerization.
A facile synthesis of 1H-indazoles featuring a Cu(OAc)2-catalyzed N-N bond formation using oxygen as the terminal oxidant is described. The reaction of readily available 2-aminobenzonitriles with various organometallic reagents led to o-aminoaryl N-H ketimine species. The subsequent Cu(OAc)2-catalyzed N-N bond formation in DMSO under oxygen afforded a wide variety of 1H-indazoles in good to excellent yields.
Half-sandwich iridium complexes bearing hydroxyindanimine ligands were synthesized and employed as catalysts for the ROMP and vinyl-type polymerization of norbornene in the presence of methylaluminoxane (MAO).
An efficient synthesis of quinazolines based on an iron-catalyzed C(sp)-H oxidation and intramolecular C-N bond formation using tert-BuOOH as the terminal oxidant is described. The reaction of readily available 2-alkylamino benzonitriles with various organometallic reagents led to 2-alkylamino N-H ketimine species. The FeCl-catalyzed C(sp)-H oxidation of the alkyl group employing tert-BuOOH followed by intramolecular C-N bond formation and aromatization afforded a wide variety of 2,4-disubstituted quinazolines in good to excellent yields.
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