Facile Synthesis of Bis(isoindolinone) through Carbonylative Cyclization and Dimerization of Phenylimine with Nickel(0) Complexes

A simple and convenient synthetic method for obtaining the novel bis(isoindolinones) 2a−d starting from aryl chlorides is described, using phenylimines with stoichiometric amounts of tetrakis(trimethylphosphine)nickel(0) as starting materials under a CO atmosphere (1 bar) at room temperature. The formation mechanism was proposed and discussed. The intermediate chelate arylnickel(II) complex 5d was also isolated and structurally characterized

Aerobic Oxidation of 2,3,6-Trimethylphenol to Trimethyl-1,4-benzoquinone with Copper(II) Chloride as Catalyst in Ionic Liquid and Structure of the Active Species

TMQ is an important precursor in industrial vitamin E synthesis. We report a “green chemistry approach” with respect to the highly selective and environmentally friendly oxidation of 2,3,6-trimethylphenol (TMP) to trimethyl-1,4-benzoquinone (TMQ) with molecular oxygen as oxidant and a copper catalyst immobilized in a molten salt. n-Butanol as co-solvent has a positive effect on the activity and selectivity. The structurally characterized catalyst, a 1-n-butyl-3-methylimidazolium oxotetracuprat, is formed in situ via hydrolysis of CuCl2 in the presence of imidazolium chloride. We propose a mechanism of oxidative phenolate activation at a [Cu4(μ4-O)]6+ core as electronically coupled electron acceptor, formation of a copper-bound phenolate radical anion, spin delocalization into the aromatic ring, and attack by triplet oxygen at the para position. Attack of Cu(I) as reduction equivalent at the peroxy radical, proton-mediated elimination of a copper(II)-hydroxo species, will either substitute a copper(I) site in the reduced oxo cluster or take up an electron from the reduced mixed valent cluster [Cu4(μ4-O)]6+ to regenerate the oxidized cluster as the active electron acceptor

Simple Synthesis of (Triphenylphosphoniomethylidene)(pentamethylcyclopentadienyl)titanium(II) Dichloride and Its Unexpected Reduction To Form a Trinuclear Titanium Cluster

The novel titanium phosphoniomethylidene complex [Cp*TiCl2(−CHPPh3)] (2; Cp* = η-C5Me5) was obtained via a transylidation reaction of Cp*TiCl3 (1) with 2 equiv of the phosphorus ylide Ph3PCH2. The trinuclear titanium(III) cluster [Cp*Ti(μ-Cl)Cl]3 (3) was formed through reduction of complex 2 with CO. Complexes 2 and 3 were structurally characterized by X-ray diffraction

N-Assisted Carbon−Hydrogen Bond Activation by Cobalt(I) Complexes

Reactions of 2-(4′-R-phenylazo)-4-methylphenols (R = Me (1), Br (2)) with Co(PMe3)3Cl afford two organocobalt(III) complexes, Co(PMe3)2Cl(Me(C6H3O∩NNC6H3R)·(H2NC6H4R)) (R = Me (3), Br (4)), whereas the reactions of 1 and 2 with Co(PMe3)4 and Co(PMe3)4Me afford the dinuclear complex [Co2(PMe3)4(MeC6H3O∩NH)2] (7) with the cleavage of the NN bond. Crystal structures of 3, 4, and 7 were determined by X-ray crystallography

Activation of sp³ Carbon−Hydrogen Bonds by Cobalt and Iron Complexes and Subsequent C−C Bond Formation

The sp3 C−H bond activation induced by CoMe(PMe3)4 and FeMe2(PMe3)4 was investigated. C(sp3)-cyclometalated complexes, based on diphosphinito PCP ligand (Ph2POCH2)2CH2, Co{(Ph2POCH2)2CH}(PMe3)2 (1), and Fe{(Ph2POCH2)2MeC}(H)(PMe3)2 (2), were obtained under mild conditions. Iodomethane is oxidatively added to 1, affording Co{(Ph2POCH2)2CH}(PMe3)(Me)(I) (3). Monocarbonylation of the hydrido-iron complex 2 occurs with substitution of a trimethylphosphine ligand trans to the hydrido ligand, affording Fe{(Ph2POCH2)2MeC}(H)(CO)(PMe3) (4). The reaction of 2 with phenylacetylene delivered the demetalated new diphosphine ligand (Ph2POCH2)2CHCH3 (6) and bis(phenylethinyl)iron complex Fe(PhCC)2(PMe3)4 (5). The new complexes 1−4 were characterized by spectroscopic methods and by X-ray diffraction analysis

Activation of sp³ Carbon−Hydrogen Bonds by Cobalt and Iron Complexes and Subsequent C−C Bond Formation

The sp3 C−H bond activation induced by CoMe(PMe3)4 and FeMe2(PMe3)4 was investigated. C(sp3)-cyclometalated complexes, based on diphosphinito PCP ligand (Ph2POCH2)2CH2, Co{(Ph2POCH2)2CH}(PMe3)2 (1), and Fe{(Ph2POCH2)2MeC}(H)(PMe3)2 (2), were obtained under mild conditions. Iodomethane is oxidatively added to 1, affording Co{(Ph2POCH2)2CH}(PMe3)(Me)(I) (3). Monocarbonylation of the hydrido-iron complex 2 occurs with substitution of a trimethylphosphine ligand trans to the hydrido ligand, affording Fe{(Ph2POCH2)2MeC}(H)(CO)(PMe3) (4). The reaction of 2 with phenylacetylene delivered the demetalated new diphosphine ligand (Ph2POCH2)2CHCH3 (6) and bis(phenylethinyl)iron complex Fe(PhCC)2(PMe3)4 (5). The new complexes 1−4 were characterized by spectroscopic methods and by X-ray diffraction analysis

Simple Synthesis of (Triphenylphosphoniomethylidene)(pentamethylcyclopentadienyl)titanium(II) Dichloride and Its Unexpected Reduction To Form a Trinuclear Titanium Cluster

The novel titanium phosphoniomethylidene complex [Cp*TiCl2(−CHPPh3)] (2; Cp* = η-C5Me5) was obtained via a transylidation reaction of Cp*TiCl3 (1) with 2 equiv of the phosphorus ylide Ph3PCH2. The trinuclear titanium(III) cluster [Cp*Ti(μ-Cl)Cl]3 (3) was formed through reduction of complex 2 with CO. Complexes 2 and 3 were structurally characterized by X-ray diffraction

Simple Synthesis of (Triphenylphosphoniomethylidene)(pentamethylcyclopentadienyl)titanium(II) Dichloride and Its Unexpected Reduction To Form a Trinuclear Titanium Cluster

The novel titanium phosphoniomethylidene complex [Cp*TiCl2(−CHPPh3)] (2; Cp* = η-C5Me5) was obtained via a transylidation reaction of Cp*TiCl3 (1) with 2 equiv of the phosphorus ylide Ph3PCH2. The trinuclear titanium(III) cluster [Cp*Ti(μ-Cl)Cl]3 (3) was formed through reduction of complex 2 with CO. Complexes 2 and 3 were structurally characterized by X-ray diffraction

N-Assisted Carbon−Hydrogen Bond Activation by Cobalt(I) Complexes

Reactions of 2-(4′-R-phenylazo)-4-methylphenols (R = Me (1), Br (2)) with Co(PMe3)3Cl afford two organocobalt(III) complexes, Co(PMe3)2Cl(Me(C6H3O∩NNC6H3R)·(H2NC6H4R)) (R = Me (3), Br (4)), whereas the reactions of 1 and 2 with Co(PMe3)4 and Co(PMe3)4Me afford the dinuclear complex [Co2(PMe3)4(MeC6H3O∩NH)2] (7) with the cleavage of the NN bond. Crystal structures of 3, 4, and 7 were determined by X-ray crystallography

Imine Nitrogen Bridged Binuclear Nickel Complexes via N–H Bond Activation: Synthesis, Characterization, Unexpected C,N-Coupling Reaction, and Their Catalytic Application in Hydrosilylation of Aldehydes

The reactions of NiMe₂(PMe₃)₃ with 2,6-difluoroarylimines were explored. As a result, a series of binuclear nickel complexes (<b>5</b>–<b>8</b>,<b> 11</b>) were synthesized. Meanwhile, from the reactions of NiMe₂(PMe₃)₃ with [2-CH₃C₆H₄-C­(NH)-2,6-F₂C₆H₃] (<b>9</b>) and [2,6-(CH₃)₂C₆H₃-C­(NH)-2,6-F₂C₆H₃] (<b>10</b>), two unexpected C,N-coupling products (<b>12</b> and <b>13</b>) were obtained. It is believed that these coupling reactions underwent activation of the N–H and C–F bonds. The binuclear nickel complexes showed excellent catalytic activity in the hydrosilylation of aldehydes. The mechanism of the reaction was studied through stoichiometric reactions, and the double-(η²-Si–H)–Ni^II intermediate was detected by in situ ¹H NMR spectroscopy, which may be the key point in the catalytic cycle