Tetra­aqua­bis{μ2-2,7-bis­[(2,6-diisopropyl­phen­yl)imino­meth­yl]naphthalene-1,8-diolato}di-μ3-hydroxido-di-μ2-hydroxido-bis­(trimethyl­phosphine oxide)tetra­nickel(II)–trimethyl­phosphine oxide–diethyl ether–water (1/2/2/2)

The title complex, [Ni4(C36H40N2O2)2(OH)4(C3H9OP)2(H2O)4]·2C4H10O·2C3H9OP·2H2O, is centrosymmetric with a central core that can be described as a defect double cubane. The four metal ions in the cluster are held together by four bridging hydroxide groups. Each NiII atom adopts a distorted octa­hedral geometry

Phosph(on/in)ate-Bridged Vanadium(IV) Dimers: Synthesis and Characterization

A series of dinuclear organophosphorus-bridged complexes of the general formula {(LVO­(μ-O₂PRR′)}₂ [L = η⁵-cyclopentadienyltris­(diethylphosphito-κ¹<i>P</i>) cobaltate­(III)] has been synthesized as a structural model for the industrially used vanadium phosphate oxidation catalysts. These dimeric species contain two vanadium centers in a VO₆ environment bridged by O–P–O units. These complexes have been characterized via spectral and magnetic analyses. Structural parameters have been analyzed through X-ray diffraction. The dimers generally exist in either a <i>cis/cis</i>-anti or retracted chair conformation in the solid state. The syntheses, structural, spectral, and magnetic data are presented and discussed here

Phosph(on/in)ate-Bridged Vanadium(IV) Dimers: Synthesis and Characterization

A series of dinuclear organophosphorus-bridged complexes of the general formula {(LVO­(μ-O₂PRR′)}₂ [L = η⁵-cyclopentadienyltris­(diethylphosphito-κ¹<i>P</i>) cobaltate­(III)] has been synthesized as a structural model for the industrially used vanadium phosphate oxidation catalysts. These dimeric species contain two vanadium centers in a VO₆ environment bridged by O–P–O units. These complexes have been characterized via spectral and magnetic analyses. Structural parameters have been analyzed through X-ray diffraction. The dimers generally exist in either a <i>cis/cis</i>-anti or retracted chair conformation in the solid state. The syntheses, structural, spectral, and magnetic data are presented and discussed here

Suppression of β-Hydride Chain Transfer in Nickel(II)-Catalyzed Ethylene Polymerization via Weak Fluorocarbon Ligand–Product Interactions

The synthesis and characterization of two neutrally charged Ni­(II) ethylene polymerization catalysts, [2-<i>tert</i>-butyl-6-((2,6-(3,5-dimethylphenyl)­phenylimino)­methyl)­phenolato]­nickel­(II) methyl trimethylphosphine (<b>(CH</b>_<b>3</b><b>)­FI-Ni</b>) and [2-<i>tert</i>-butyl-6-((2,6-(3,5-bis­(trifluoromethyl)­phenyl)­phenylimino)­methyl)­phenolato]­nickel­(II) methyl trimethylphosphine (<b>(CF</b>_<b>3</b><b>)­FI-Ni</b>) are reported. In the presence of a Ni­(COD)₂ cocatalyst, these catalysts produce markedly different polyethylenes: densely branched oligomers with <i>M</i>_w = 1.4 × 10³ g mol^–1 for <b>(CH</b>_<b>3</b><b>)­FI-Ni</b> vs lightly branched polyethylenes with <i>M</i>_w = 92 × 10³ g mol^–1 for <b>(CF</b>_<b>3</b><b>)­FI-Ni</b> and with ∼6.5× the polymerization activity and with much greater performance thermal stability. HOESY 2D ¹⁹F,¹H NMR spectra of a model Ni-ethyl compound, [2-<i>tert</i>-butyl-6-((2,6-(3,5-bis­(trifluoromethyl)­phenyl)­phenylimino)­methyl)­phenolato]­nickel­(II) ethyl 2,4-lutidine (<b>(CF</b>_<b>3</b><b>)­FI-Ni-Et</b>), indicate non-negligible C_β–H_β···F₃C through-space dipolar interactions, and molecular modeling reveals that C_β–H_β···F­(C) distances can be as small as ∼2.61 Å during the polymerization process. Furthermore, there is no structural or spectroscopic evidence for fluorocarbon inductive effects on the structure, bonding, and reactivity of these complexes, and a catalyst with CF₃ introduced β to the imino N produces only low-<i>M</i>_w oligomers with low activity. These results argue that weak (ligand)­C–F···H–C­(polymer) interactions can significantly influence the chain transfer characteristics of these catalysts

Suppression of β-Hydride Chain Transfer in Nickel(II)-Catalyzed Ethylene Polymerization via Weak Fluorocarbon Ligand–Product Interactions

The synthesis and characterization of two neutrally charged Ni­(II) ethylene polymerization catalysts, [2-<i>tert</i>-butyl-6-((2,6-(3,5-dimethylphenyl)­phenylimino)­methyl)­phenolato]­nickel­(II) methyl trimethylphosphine (<b>(CH</b>_<b>3</b><b>)­FI-Ni</b>) and [2-<i>tert</i>-butyl-6-((2,6-(3,5-bis­(trifluoromethyl)­phenyl)­phenylimino)­methyl)­phenolato]­nickel­(II) methyl trimethylphosphine (<b>(CF</b>_<b>3</b><b>)­FI-Ni</b>) are reported. In the presence of a Ni­(COD)₂ cocatalyst, these catalysts produce markedly different polyethylenes: densely branched oligomers with <i>M</i>_w = 1.4 × 10³ g mol^–1 for <b>(CH</b>_<b>3</b><b>)­FI-Ni</b> vs lightly branched polyethylenes with <i>M</i>_w = 92 × 10³ g mol^–1 for <b>(CF</b>_<b>3</b><b>)­FI-Ni</b> and with ∼6.5× the polymerization activity and with much greater performance thermal stability. HOESY 2D ¹⁹F,¹H NMR spectra of a model Ni-ethyl compound, [2-<i>tert</i>-butyl-6-((2,6-(3,5-bis­(trifluoromethyl)­phenyl)­phenylimino)­methyl)­phenolato]­nickel­(II) ethyl 2,4-lutidine (<b>(CF</b>_<b>3</b><b>)­FI-Ni-Et</b>), indicate non-negligible C_β–H_β···F₃C through-space dipolar interactions, and molecular modeling reveals that C_β–H_β···F­(C) distances can be as small as ∼2.61 Å during the polymerization process. Furthermore, there is no structural or spectroscopic evidence for fluorocarbon inductive effects on the structure, bonding, and reactivity of these complexes, and a catalyst with CF₃ introduced β to the imino N produces only low-<i>M</i>_w oligomers with low activity. These results argue that weak (ligand)­C–F···H–C­(polymer) interactions can significantly influence the chain transfer characteristics of these catalysts

Ni(II) Phenoxyiminato Olefin Polymerization Catalysis: Striking Coordinative Modulation of Hyperbranched Polymer Microstructure and Stability by a Proximate Sulfonyl Group

The synthesis, structural characterization, and ethylene polymerization properties of two neutrally charged Ni­(II) phenoxyiminato catalysts are compared and contrasted. Complex FI-SO₂-Ni features a −SO₂– group embedded in the ligand skeleton, whereas control FI-CH₂-Ni has the −SO₂– replaced by a −CH₂– functionality. In comparison with FI-CH₂-Ni, at 25 °C, FI-SO₂-Ni is 18 times more active, produces polyethylene with 3.2 times greater <i>M</i>_W and 1.5 times branch content, and is significantly more thermally stable. The FI-SO₂-Ni-derived polymer is a hyperbranched polyethylene (148 branches 1000 C^–1, <i>M</i>_W = 3500<i>g</i> mol^–1) versus that from FI-CH₂-Ni (98 branches 1000 C^–1, <i>M</i>_W = 1100<i>g</i> mol^–1). DFT calculations argue that the distinctive FI-SO₂-Ni catalytic behavior versus that of FI-CH₂-Ni is associated with nonnegligible OSO···Ni interactions involving the activated catalyst