Journal of Organometallic Chemistry最新文献

Two Ln₄ clusters with the formula of [Ln₄(acac)₄(µ₃OH)₂(L)₆]·xCH₃CN (Ln=Sm (1), Yb (2)) were synthesized through the reaction of Ln(acac)₃·2H₂O (Hacac = acetylacetone) with the bidentate flexible ligand 5-benzylidene-1,5-dihydroquinolin-8-ol. X-ray diffraction studies indicate that clusters 1 and 2 are isostructural and processes a rhombic-shaped Ln₄ core. The coordination geometry of each Ln(III) ion is characterized as a distorted square antiprism. Notably, clusters 1 and 2 exhibit outstanding catalytic performance for the cycloaddition of CO₂ with epoxides and for Knoevenagel condensation under mild conditions.

Polyethylene wax is a highly useful material, and its diverse topological structures may have a significant impact on its applications. In this study, we have devised and synthesized a series of unilateral benzocycloalkyl α-diimine nickel catalysts. These nickel catalysts exhibited very high activities (1.06 to 10.25 × 10⁶ g mol^-1·h^-1) and yielded branched (37–97/1000 C) polyethylene waxes with low molecular weights (M_n = 0.49 to 2.01 kg mol^-1) and variable molecular weight distributions (1.79–35.05) in ethylene polymerization. Polymerization conditions such as pressure and temperature and catalyst structure such as backbone and axial substituents have an important influence on the polymerization activity and the properties of the resulting polyethylene waxes. High-temperature NMR reveals that these branched polyethylenes primarily feature short-chain branches, such as the methyl group, and exhibit a topology resembling that of low-molecular-weight linear low-density polyethylene (LLDPE).

New (trifluorosilyl)propyl derivatives of cyclic dicarboxylic acid imides 1-[3-(trifluorosilyl)propyl]pyrrolidine-2,5‑dione, 1-[3-(trifluorosilyl)propyl]piperidine-2,6‑dione and 2-[3-(trifluorosilyl)propyl]-1H-isoindole-1,3(2H)‑dione were synthesized and structurally characterized by FTIR, NMR spectroscopy, mass spectrometry and elemental analysis. Intramolecular coordination interaction O→Si and the influence of the hydrocarbon chain length on the strength of the coordination interaction in Si-fluoroethyl and Si-fluoropropyl derivatives of cyclic imides of dicarboxylic acids were characterized by DFT calculations. The geometric, energetic and electronic characteristics of the investigated molecules were also determined. The intramolecular O→Si coordination bond, closing the six-membered chelate cycle SiCCN(C=O), is observed in the (trifluorosilyl)ethyl derivative phthalimide in the gas, and in the (trifluorosilyl)ethyl derivative succinimide the O→Si coordination bond is observed both in the gas phase and in DMSO solution. The coordination bond O→Si, closing the seven-membered chelate cycle SiCCCN(C=O), is found in the (trifluorosilyl)propyl derivative succinimide in the gas phase. Quantum chemical calculations were carried out at the M06/6–311G** and MP2/6–311++G**//M06/6–311G** levels with the 6–311G** basis set.

A novel deep red-emitting dinuclear platinum (II) complex, (TPA2niq)₂Pt₂(C₈OXT)₂, featuring a donor-π-acceptor (D-π-A) type ligand, was synthesized and characterized. Here, TPA2niq represents the 4-(tert-butyl)-N-(4-(tert-butyl)phenyl)-N-(4-(6-(isoquinolin-1-yl)naphthalen-2-yl)phenyl)aniline unit, while C₈OXT was the abbreviation for the bridging ligand 5-(4-octyloxyphenyl)-1,3,4-oxadiazole-2-thiol. Its photophysical, electrochemical, and electroluminescent characteristics were primarily studied. It was found that (TPA2niq)₂Pt₂(C₈OXT)₂ exhibited a saturated deep red emission with a peak at 686 nm in dichloromethane. Furthermore, the (TPA2niq)₂Pt₂(C₈OXT)₂-doped polymer electroluminescent devices (PLEDs), fabricated through a solution process, exhibited outstanding electroluminescence (EL) properties, with an emission peak at 684 nm, a maximum external quantum efficiency (EQE) of 3.78%, and a maximum radiant emittance of 4478 mW/Sr/m². By incorporating the D-π-A type ligand into the dinuclear platinum (II) complex, the PLEDs achieved efficient deep red emission.

A novel multi-site receptor 1 bearing four ferrocenyl arms comprising benzimidazolium moieties was synthesized and structurally characterized by IR, NMR, elemental analysis, mass spectra. Moreover, the structure of receptor 1 was confirmed by X-ray crystallography, it was clear that the cationic heterocyclic was interacted with PF₆⁻ through C–H···F hydrogen bonds. Its electrochemical properties of sensing the various anions were investigated by cyclic voltammograms (CV) and differential pulse voltammetry (DPV), the receptor 1 displayed a significant cathodic shift for F⁻and OH⁻. The addition of F⁻ and OH⁻to the solution of receptor 1 resulted in obvious absorption changes in the UV–Vis spectrum, showing that receptor 1 was an excellent sensor for these analytes (F⁻: LOD = 3.11 × 10⁻⁶ M, LOQ = 1.03 × 10⁻⁵ M, K_a = 5.83 × 10⁵ M⁻¹; and OH^–: LOD = 1.36 × 10⁻⁶ M, LOQ = 4.11 × 10⁻⁵ M, K_a = 9.03 × 10⁵ M⁻¹). ¹H NMR titrations demonstrated that anion was recognized by receptor 1 through (C–H)⁺···X⁻ and C–H···X hydrogen bonds, the binding process involve initial formation of hydrogen bond and followed by deprotonation.

Following the recent isolation and structural characterization of the first low-valent Ga^I complex with a monoanionic dipyrromethenide ligand (DPM), herein (DPM)Ga^I complexes with bulky aryl-substituents in the 1- and 9-positions are described. This study focusses on three DPM ligands with mesityl substituents (^MesDPM), 2,6-diisopropylphenyl substituents (^DIPPDPM), or 10-isopropyl-9-anthracenyl substituents (^iPr-AnthDPM); the synthesis to the latter unknown ligand is described. The precursors (^RDPM)GaI₂ were obtained by reaction of the corresponding alkali metal complexes (^RDPM)M (M = Na or K) with GaI₃ and characterized by X-ray diffraction. Crystal structures show the efficient shielding of the GaI₂ unit by two flanking aryl groups. In a subsequent reduction step, (^DIPPDPM)Ga^I and (^iPr-AnthDPM)Ga^I have been isolated. Comparison of the crystal structure of (^DIPPDPM)Ga^I with that of a similar β-diketiminate Ga^I complex shows that the Ga center in the DPM complex is well shielded by flanking DIPP substituents. Despite this favorable ligand geometry, isolation of the corresponding (DPM)Ga=N(SiMe₃) complexes failed due to further reaction with a second equivalent of Me₃SiN₃. This resulted in clean formation of the tetrazagallole complex (^tBuDPM)Ga[N₄(SiMe₃)₂] and the amide/azide combination (^iPr-AnthDPM)Ga(N₃)N(SiMe₃)₂, both structurally characterized by X-ray diffraction. Selective formation of both complexes shows that the substituents in the DPM ligand effectively control the course of the reaction. DFT calculations show that independent of the substituent (tBu, DIPP, or iPr-Anth) the amide/azide combination is always circa 20 kcal/mol more stable than the tetrazagallole product. The latter must therefore be formed by kinetic control.

A kind of magnetic hybrid organic-inorganic nanoparticles containing Ru metal (Fe₃O₄@SiO₂-FPBA-Ru) was prepared. It was spherical with the characteristic lattice fringe of ruthenium atom. The size was in the range of 5–15 nm and it contained 0.30 mmol/g Ru. Its saturation magnetization value was 15.95 emu/g, which could be easily and efficiently recovered from solution through an external magnet. It was also stable below 240°C and hot filtration experiment proved Ru wasn't leaked from Fe₃O₄@SiO₂-FPBA-Ru in 70°C oxidation reaction. It could be recovered and reused at least 7 cycles. The low amount of Fe₃O₄@SiO₂-FPBA-Ru (75 mmol%) could convert the 99 % of 1-phenylethanol to acetophenone under solvent-free system, which verified its green and environment-friendly properties. The yield was exceed that of homogeneous (RuCl₃, 85 %). Beside this, the TON (5181), TOF (7430 h⁻¹) in oxidation of 1-phenylethanol and high conversion yields for a series of oxidation reactions of aromatic secondary alcohols proved the high catalytic ability of Fe₃O₄@SiO₂-FPBA-Ru. These laid a foundation for its industrial applications.

The current study highlights on the synthesis and characterization of aqua-complexes of the fac-[M(CO)₃]⁺ (M = Re and ^99mTc) core with pyrimidine-4,6-dicarboxylic acid (H₂pmdc) and its monoester 6-(ethoxycarbonyl)pyrimidine-4-carboxylic acid (Hetpmdc), which are the model for future design of imaging and therapeutic radiopharmaceuticals. Complexes [M(CO)₃(OH₂)(Hpmdc)] (M = Re (1) and ^99mTc (2)) were formed from the reaction of H₂pmdc with [Re(CO)₅Br] in water and aqueous solution of [^99mTc(CO)₃(OH₂)₃]⁺ respectively. The reaction of [Re(CO)₅Br] with H₂pmdc in ethanol (EtOH) has also studied and led to the complex [Re(CO)₃(OH₂)(etpmdc)] (3), where etpmdc⁻is 6-(ethoxycarbonyl)pyrimidine-4-carboxylate anion which was formed from the mono-esterification of H₂pmdc in parallel with its coordination to the fac-[Re(CO)₃]⁺ unit. The complex [^99mTc(CO)₃(OH₂)(etpmdc)] (4) was formed in parallel with 2 by reacting H₂pmdc with aqueous solution of [^99mTc(CO)₃(OH₂)₃]⁺ and ethanol. The chemical identification of 1 and 3 was achieved by using ¹H NMR, ¹³C NMR, IR, ESI-MS and elemental analysis. Complex 3 was furtherly identified by using single crystal X-ray crystallography. The structural similarities of 1 and 2 was assessed by coinjection of both complexes in the HPLC with UV/Vis detection coupled with a γ-detector followed by comparison of retention times of the γ-peak of 2 and the UV-peak of 1 which allowed unambiguous identification of 2. Similarly, the formation of complex [^99mTc(CO)₃(OH₂)(etpmdc)] (4) in parallel with 2 was assessed by coinjection of complexes 1 and 3 with the product from the reaction of H₂pmdc with aqueous solution of [^99mTc(CO)₃(OH₂)₃]⁺ and ethanol in the same HPLC as one used for the structural identification of 2 followed by comparison of retention times of the γ-peaks of 2 and 4 and the UV-peaks of 1 and 3.

In this study, we have explored the formation of ferrocenyl-substituted pyridines by utilizing an electrocyclization process with α,β,γ,δ-unsaturated aldehydes and aqueous ammonia solutions. The reactions occur under solvent-free conditions, although, if needed, water can be used as a solvent; it is a convenient and effective technique, yielding the desired product in just 6 hours. The protocol demonstrates promising results with all the variants of α,β,γ,δ-unsaturated aldehydes consisting of ferrocenyl, phenyl and acrylates derivatives. All the newly synthesised ferrocenyl pyridine derivatives were fully characterized by the spectroscopic analysis, moreover, molecular structure of 2-(Naphthalene-2-yl)-4-ferrocenyl pyridine (3g) was established by the Single Crystal X-ray Diffraction analysis. Some of the ferrocenyl-substituted pyridines were also studied by UV-vis absorption spectroscopy and electrochemical analyses, a comparative study about the effect of electron donating and withdrawing groups has also been discussed.

We present the synthesis and structural characterization of a novel dimeric sodium complex with the chemical composition [{Ph₂Si(H)PhN}Na(THF)₂]₂ (Na-1) supported by N,1,1-triphenylsilanamine fragment. The single-crystal X-ray diffraction analysis of complex Na-1 in the solid state reveals the coordination of sodium ion with N and O atoms of the triphenylsilanamine unit, forming a four-membered ring. The sodium complex also demonstrates excellent activity as a pre-catalyst towards the cyanosilylation of a wide array of ketones with trimethylsilyl cyanide (TMSCN) to afford trimethylsilyloxypropanenitriles in excellent yield (up to 99 %) in a shorter time under mild and solvent-free reaction conditions and exhibits a greater tolerance to a variety of ketones bearing electron-withdrawing and electron-donating functional groups. The plausible mechanism of cyanosilylation of ketones catalyzed by the complex Na-1 is also proposed.