Euphorbia jolkinii Boiss.

原著和名: イハタイゲキ科名: トウダイグサ科 = Euphorbiaceae採集地: 島根県 隠岐 島後 (隠岐 島後)採集日: 1977/4/21採集者: 萩庭丈壽整理番号: JH025796国立科学博物館整理番号: TNS-VS-97579

Titanium and zirconium permethylpentalene complexes, Pn*MCpRX, as ethylene polymerization catalysts

A family of group 4 permethylpentalene complexes, Pn∗MCpRX (M = Ti, Zr; CpR = Cp, CpMe, CptBu, CpnBu, CpMe3, Ind; X = Cl, Me), has been synthesized and fully characterized by multinuclear NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction studies. These complexes were immobilized on an insoluble polymethylaluminoxane (sMAO), MAO-modified silica (ssMAO), and a MAO-modified layered double hydroxide (LDH-MAO). The effect of substitution around the Cp ligand was examined in relation to their performance (activity, Mw, PDI, polymer morphology) for ethylene polymerization measured both in solution and in slurry phase. Maximum solution-phase activities of 3585 kg/mol·h·bar were recorded at modest [Zr]:[Al] ratios of 1:250. These were compared to the activities recorded using the equivalent solid-supported complexes, and it was observed that sMAO was a superior support material with average increases in activity of 5.3 and 2.3 times relative to ssMAO and LDH-MAO, respectively. Most striking was the observation that slurry-phase ethylene polymerization activities using equivalent precatalysts supported on sMAO showed enhanced performance compared to the solution phase up to a maximum of 4486 kg/mol·h·bar

CO₂ activation by permethylpentalene amido zirconium complexes

We report the synthesis and characterisation of new permethylpentalene zirconium bis(amido) and permethylpentalene zirconium cyclopentadienyl mono(amido) complexes, and their reactivity with carbon dioxide

Multimetallic permethylpentalene hydride complexes

The synthesis and characterization of group 4 permethylpentalene (Pn* = C8Me6) hydride complexes are explored; in all cases, multimetallic hydride clusters were obtained. Group 4 lithium metal hydride clusters were obtained when reacting the metal dihalides with hydride transfer reagents such as LiAlH4, and these species featured an unusual hexagonal bipyramidal structural motif. Only the zirconium analogue was found to undergo hydride exchange in the presence of deuterium. In contrast, a trimetallic titanium hydride cluster was isolated on reaction of the titanium dialkyl with hydrogen. This diamagnetic, mixed valence species was characterized in the solid state, as well as by solution electron paramagnetic resonance and nuclear magnetic resonance spectroscopy. The structure was further probed and corroborated by density functional theory calculations, which illustrated the formation of a metal-cluster bonding orbital responsible for the diamagnetism of the complex. These permethylpentalene hydride complexes have divergent structural motifs and reactivity in comparison with related classical cyclopentadienyl analogues

Time-resolved in situ X-ray diffraction reveals metal-dependent metal-organic framework formation.

Versatility in metal substitution is one of the key aspects of metal-organic framework (MOF) chemistry, allowing properties to be tuned in a rational way. As a result, it important to understand why MOF syntheses involving different metals arrive at or fail to produce the same topological outcome. Frequently, conditions are tuned by trial-and-error to make MOFs with different metal species. We ask: is it possible to adjust synthetic conditions in a systematic way in order to design routes to desired phases? We have used in situ X-ray powder diffraction to study the solvothermal formation of isostructural M2 (bdc)2 dabco (M=Zn, Co, Ni) pillared-paddlewheel MOFs in real time. The metal ion strongly influences both kinetics and intermediates observed, leading in some cases to multiphase reaction profiles of unprecedented complexity. The standard models used for MOF crystallization break down in these cases; we show that a simple kinetic model describes the data and provides important chemical insights on phase selection

Time-resolved in situ X-ray diffraction reveals metal-dependent metal-organic framework formation.

Versatility in metal substitution is one of the key aspects of metal-organic framework (MOF) chemistry, allowing properties to be tuned in a rational way. As a result, it important to understand why MOF syntheses involving different metals arrive at or fail to produce the same topological outcome. Frequently, conditions are tuned by trial-and-error to make MOFs with different metal species. We ask: is it possible to adjust synthetic conditions in a systematic way in order to design routes to desired phases? We have used in situ X-ray powder diffraction to study the solvothermal formation of isostructural M2 (bdc)2 dabco (M=Zn, Co, Ni) pillared-paddlewheel MOFs in real time. The metal ion strongly influences both kinetics and intermediates observed, leading in some cases to multiphase reaction profiles of unprecedented complexity. The standard models used for MOF crystallization break down in these cases; we show that a simple kinetic model describes the data and provides important chemical insights on phase selection

Reversible coordination of N<inf>2</inf>and H<inf>2</inf>to a homoleptic: S = 1/2 Fe(i) diphosphine complex in solution and the solid state

The synthesis and characterisation of the S = 1/2 Fe(i) complex [Fe(depe)2]+[BArF4]-([1]+[BArF4]-), and the facile reversible binding of N2and H2in both solution and the solid state to form the adducts [1·N2]+and [1·H2]+, are reported. Coordination of N2in THF is thermodynamically favourable under ambient conditions (1 atm; ΔG298= -4.9(1) kcal mol-1), while heterogenous binding is more favourable for H2than N2by a factor of ∼300. [1·H2]+[BArF4]-represents a rare example of a well-defined, open-shell, non-classical dihydrogen complex, as corroborated by ESR spectroscopy. The rapid exchange between N2and H2coordination under ambient conditions is unique for a paramagnetic Fe complex

Reversible coordination of N2 and H2 to a homoleptic S = 1/2 Fe(I) diphosphine complex in solution and the solid state

The synthesis and characterisation of the S = 1/2 Fe(I) complex [Fe(depe)2]+[BArF4]− ([1]+[BArF4]−), and the facile reversible binding of N2 and H2 in both solution and the solid state to form the adducts [1·N2]+ and [1·H2]+, are reported. Coordination of N2 in THF is thermodynamically favourable under ambient conditions (1 atm; ΔG298 = −4.9(1) kcal mol−1), while heterogenous binding is more favourable for H2 than N2 by a factor of ∼300. [1·H2]+[BArF4]− represents a rare example of a well-defined, open-shell, non-classical dihydrogen complex, as corroborated by ESR spectroscopy. The rapid exchange between N2 and H2 coordination under ambient conditions is unique for a paramagnetic Fe complex