Three-Coordinate and Four-Coordinate Cobalt Hydride Complexes That React with Dinitrogen

Three-Coordinate and Four-Coordinate Cobalt Hydride Complexes That React with Dinitroge

Three-Coordinate and Four-Coordinate Cobalt Hydride Complexes That React with Dinitrogen

Three-Coordinate and Four-Coordinate Cobalt Hydride Complexes That React with Dinitroge

Study of the Conformationally Flexible, Wide Bite-Angle Diphosphine 4,6-Bis(3-diisopropylphosphinophenyl)dibenzofuran in Rhodium(I) and Palladium(II) Coordination Complexes

The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as iPrDPDBFphos) was prepared and studied for its potential as a trans-chelating ligand in transition-metal coordination complexes. In the rhodium norbornadiene complex [(iPrDPDBFphos)Rh(NBD)]BF4, which has been characterized with multinuclear NMR spectroscopy, X-ray crystallography, and electrochemical studies, the ligand binds in cis fashion. In the bis(acetonitrile) complexes of rhodium and palladium [(iPrDPDBFphos)M(CH3CN)2](BF4)n (M = Rh, Pd; n = 1, 2), the ligand adopts a trans coordination geometry. Density functional theory (DFT, M06-L) calculations predict that the trans conformer is energetically more favorable than the cis by 3.5 kcal/mol. Cyclic voltammograms of the bis(acetonitrile) Pd(II) and Rh(I) complexes contain reversible and quasi-reversible reduction events, respectively, which are preliminarily assigned as metal-based redox reactions

Study of the Conformationally Flexible, Wide Bite-Angle Diphosphine 4,6-Bis(3-diisopropylphosphinophenyl)dibenzofuran in Rhodium(I) and Palladium(II) Coordination Complexes

The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as iPrDPDBFphos) was prepared and studied for its potential as a trans-chelating ligand in transition-metal coordination complexes. In the rhodium norbornadiene complex [(iPrDPDBFphos)Rh(NBD)]BF4, which has been characterized with multinuclear NMR spectroscopy, X-ray crystallography, and electrochemical studies, the ligand binds in cis fashion. In the bis(acetonitrile) complexes of rhodium and palladium [(iPrDPDBFphos)M(CH3CN)2](BF4)n (M = Rh, Pd; n = 1, 2), the ligand adopts a trans coordination geometry. Density functional theory (DFT, M06-L) calculations predict that the trans conformer is energetically more favorable than the cis by 3.5 kcal/mol. Cyclic voltammograms of the bis(acetonitrile) Pd(II) and Rh(I) complexes contain reversible and quasi-reversible reduction events, respectively, which are preliminarily assigned as metal-based redox reactions

Synthesis, Properties, and Reactivity of Diketiminate-Supported Cobalt Fluoride Complexes

Reaction of the three-coordinate cobalt(II) methyl complex LtBuCoCH3 (LtBu = bulky β-diketiminate ligand) with (CH3)3SnF gives an interesting trimetallic complex, [LtBuCo(μ-F)2]2Sn(CH3)2 (1). Magnetic susceptibility studies indicate that 1 consists of two mixed-valence cobalt(II/III) fluoride units bridged by the organometallic tin(III) fragment [SnF2(CH3)2]−. The addition of pyridine releases the tin bridge, and the cobalt fluoride species can be isolated as the high-spin cobalt(II) complex LtBuCoF(py) (2). Treating 2 with triethylsilane in an effort to form LtBuCoH(py) gave instead the high-spin cobalt(I) complex LtBuCo(py), with elimination of H2. Attempts at catalytic or stoichiometric hydrodefluorination of fluorinated aromatics with silane using 2 as a catalyst were unsuccessful. The lack of hydrodefluorination activity may be due to H2 elimination from low-coordinate cobalt hydride complexes or from inhibition by a fourth donor to the metal

First-Row Transition-Metal Chloride Complexes of the Wide Bite-Angle Diphosphine ^iPrDPDBFphos and Reactivity Studies of Monovalent Nickel

The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as iPrDPDBFphos) has been metalated with transition metal dichlorides of zinc, cobalt, and nickel to yield (iPrDPDBFphos)MCl2 complexes. Within these compounds, the diphosphine iPrDPDBFphos adapts a wide range of bite angles (115 to 180°) as determined by X-ray crystallography. A three-coordinate planar Ni(I) species was isolated from the reduction of (iPrDPDBFphos)NiCl2 with KC8. Low-temperature electron paramagnetic resonance (EPR) measurements of (iPrDPDBFphos)NiCl allow the determination of g values (2.09, 2.14, 2.37) and hyperfine coupling constants to two 31P nuclei, Aiso = 46 × 10–4 cm–1, and one 37Cl/35Cl nucleus, A = (12, 0.7, 35) × 10–4 cm–1. Density functional theory (DFT) studies reveal the nature of the magnetic orbital to be dxy, which has σ-antibonding and π∥-antibonding interactions with the phosphorus and chloride atoms, respectively. The monovalent nickel complex reacts with substrates containing C–X bonds; and in the case of vinyl chloride, a Ni(II) vinyl species (iPrDPDBFphos)Ni(CHCH2)Cl is generated along with the Ni(II) dichloride complex. The monovalent Ni(I) chloride is an active catalyst in the Kumada cross-coupling reaction of vinyl chloride and phenyl Grignard reagent

First-Row Transition-Metal Chloride Complexes of the Wide Bite-Angle Diphosphine ^iPrDPDBFphos and Reactivity Studies of Monovalent Nickel

The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as iPrDPDBFphos) has been metalated with transition metal dichlorides of zinc, cobalt, and nickel to yield (iPrDPDBFphos)MCl2 complexes. Within these compounds, the diphosphine iPrDPDBFphos adapts a wide range of bite angles (115 to 180°) as determined by X-ray crystallography. A three-coordinate planar Ni(I) species was isolated from the reduction of (iPrDPDBFphos)NiCl2 with KC8. Low-temperature electron paramagnetic resonance (EPR) measurements of (iPrDPDBFphos)NiCl allow the determination of g values (2.09, 2.14, 2.37) and hyperfine coupling constants to two 31P nuclei, Aiso = 46 × 10–4 cm–1, and one 37Cl/35Cl nucleus, A = (12, 0.7, 35) × 10–4 cm–1. Density functional theory (DFT) studies reveal the nature of the magnetic orbital to be dxy, which has σ-antibonding and π∥-antibonding interactions with the phosphorus and chloride atoms, respectively. The monovalent nickel complex reacts with substrates containing C–X bonds; and in the case of vinyl chloride, a Ni(II) vinyl species (iPrDPDBFphos)Ni(CHCH2)Cl is generated along with the Ni(II) dichloride complex. The monovalent Ni(I) chloride is an active catalyst in the Kumada cross-coupling reaction of vinyl chloride and phenyl Grignard reagent

High-Performance Pressure-Sensitive Adhesives from Renewable Triblock Copolymers

High-Performance Pressure-Sensitive Adhesives from Renewable Triblock Copolymer

Cobalt−Dinitrogen Complexes with Weakened N−N Bonds

Cobalt−Dinitrogen Complexes with Weakened N−N Bond