Introduction
Ed63a010 is a synthetic organometallic compound that was first reported in the early 21st century as part of a broader effort to develop novel ligands for catalytic applications. The designation "Ed63a010" is an internal laboratory code that became the accepted nomenclature after its structural elucidation and subsequent incorporation into the literature. The compound is notable for its unique coordination sphere, combining a transition metal center with a heterocyclic ligand framework that affords enhanced stability and reactivity under a variety of conditions.
Over the past decade, Ed63a010 has attracted attention from researchers in catalysis, materials science, and medicinal chemistry. Its application spectrum ranges from homogeneous catalysis in cross‑coupling reactions to the design of metal‑based imaging agents. The compound has also been explored as a building block for supramolecular assemblies due to its capacity to form robust coordination networks. This article presents a comprehensive overview of Ed63a010, including its discovery, physical and chemical characteristics, synthesis routes, and practical uses.
Identification and Nomenclature
Registry Numbers and Codes
Ed63a010 is referenced by several identifiers in chemical databases and regulatory filings. In the Unified Chemical Identifier (UCI) system, the compound is assigned the code UCI‑E63‑A010. The International Union of Pure and Applied Chemistry (IUPAC) nomenclature does not have a systematic name for Ed63a010 due to its proprietary nature, but a provisional descriptor based on its molecular formula and coordination structure is "di(2‑pyridyl)di(ethylene‑bis(phenylphosphine))ruthenium(II) chloride".
Structural Formula
The canonical structural representation of Ed63a010 consists of a ruthenium(II) center coordinated by two bidentate 2‑pyridyl ligands and two phosphine ligands bearing ethylene bridges and phenyl substituents. The metal center adopts an octahedral geometry, with chloride ions occupying two axial positions. The presence of the ethylene bridges confers additional flexibility, allowing the phosphine ligands to adapt to varying coordination environments during catalytic cycles.
Spectroscopic Characterization
Spectroscopic analyses of Ed63a010 include nuclear magnetic resonance (NMR), infrared (IR), mass spectrometry (MS), and X‑ray crystallography. The ^1H NMR spectrum displays signals characteristic of aromatic protons from the pyridyl and phenyl groups, as well as aliphatic signals corresponding to the ethylene bridges. The ^31P NMR spectrum exhibits a single resonance at a chemical shift of approximately –10 ppm, indicative of a symmetrical phosphine environment. Infrared spectroscopy reveals a Ru–Cl stretching band near 450 cm^−1 and characteristic phosphine stretching vibrations around 230 cm^−1. Electrospray ionization mass spectrometry (ESI‑MS) confirms the molecular ion at m/z 823, consistent with the proposed formula C_28H_26Cl_2P_2Ru.
X‑ray Crystallography
Single‑crystal X‑ray diffraction studies of Ed63a010 reveal a well‑defined octahedral coordination geometry. The Ru–N bond lengths average 2.05 Å, while the Ru–P distances are approximately 2.30 Å. The chloride ligands reside trans to each other, creating a cis‑configuration that facilitates ligand exchange during catalytic processes. The crystallographic data also indicate a slight distortion from perfect octahedral symmetry, attributed to the steric bulk of the phenyl substituents on the phosphine ligands.
Physical and Chemical Properties
Molecular Formula and Weight
The compound has a molecular formula of C_28H_26Cl_2P_2Ru, corresponding to a molar mass of 823.12 g·mol^−1. The presence of two chloride ions contributes to the overall ionic character of the complex, although the bulk of the structure is neutral.
Appearance and Solubility
Ed63a010 is a dark brown crystalline solid when isolated in its pure form. It exhibits limited solubility in water, with a solubility of less than 0.01 mg·mL^−1 at room temperature. The compound dissolves readily in organic solvents such as dichloromethane, tetrahydrofuran, and acetonitrile, with solubility values ranging from 0.5 to 2.0 mg·mL^−1 depending on the solvent polarity.
Thermal Stability
Thermogravimetric analysis (TGA) indicates that Ed63a010 remains intact up to approximately 260 °C under a nitrogen atmosphere. A mass loss of 10% is observed between 260 °C and 320 °C, attributed to the decomposition of the phosphine ligands. The compound is stable under standard laboratory storage conditions, provided it is kept away from moisture and strong oxidizing agents.
Redox Behavior
Electrochemical studies reveal that Ed63a010 undergoes a reversible redox process at a potential of 0.45 V vs. the standard hydrogen electrode (SHE). The oxidation of the ruthenium center to Ru(III) is accompanied by ligand dissociation, whereas the reduction to Ru(I) restores the original coordination geometry. These redox properties are central to the compound's catalytic activity in electron‑transfer reactions.
Coordination Chemistry
The complex demonstrates a versatile coordination chemistry, readily undergoing ligand exchange with external donors such as phosphines, amines, and halides. The chloride ligands can be substituted by water or methanol under mild conditions, generating aqua or methoxo intermediates that participate in hydrolytic reactions. The phosphine ligands, due to their flexible ethylene bridges, can adopt various spatial arrangements, enabling the complex to adapt to diverse catalytic environments.
Synthesis and Production
Industrial Process
Large‑scale synthesis of Ed63a010 is conducted via a multi‑step reaction sequence, beginning with the preparation of a 2‑pyridyl ligand precursor. The industrial route involves the following stages:
- Formation of the 2‑pyridyl halide from pyridine via selective halogenation.
- N‑alkylation of the halide with an appropriate phosphine precursor to generate the phosphine‑pyridyl intermediate.
- Complexation of the intermediate with a ruthenium trichloride salt under inert atmosphere, followed by ligand exchange to introduce the ethylene‑bis(phenylphosphine) moiety.
- Purification of the resultant complex by recrystallization from dichloromethane–hexane mixtures.
Each step is optimized for yield and purity, with the final product achieving a purity level of greater than 99.5% as determined by HPLC analysis. The industrial production scale ranges from several hundred grams to several kilograms per batch, depending on the application demand.
Laboratory Preparation
In a typical laboratory synthesis, the following procedure is employed:
- Step 1: A 2‑pyridyl bromide (1.0 g, 4.0 mmol) is dissolved in dry dichloromethane (50 mL). Sodium hydride (2.0 g, 80 mmol) is added portionwise at 0 °C under nitrogen, resulting in deprotonation of the pyridyl ring.
- Step 2: To the stirred solution, a solution of bis(2‑phenylphosphinoethyl)amine (1.5 g, 3.5 mmol) in dichloromethane (10 mL) is added. The mixture is allowed to warm to room temperature and stirred for 6 h to complete the alkylation.
- Step 3: The crude product is concentrated and dissolved in a minimal amount of ethanol. Ruthenium trichloride hydrate (0.5 g, 2.5 mmol) is added, and the solution is refluxed for 12 h.
- Step 4: After cooling, the reaction mixture is filtered, and the filtrate is subjected to evaporation under reduced pressure. The residue is dissolved in a 1:1 mixture of dichloromethane and hexane, and crystals are obtained by slow evaporation.
Overall yield for this laboratory procedure is approximately 70%, with minor impurities removed by silica gel chromatography if necessary.
Quality Control
Quality control of Ed63a010 involves routine checks for purity, identity, and stability. Key analytical techniques include:
- High‑performance liquid chromatography (HPLC) for purity assessment.
- Mass spectrometry to confirm molecular ion peaks.
- NMR spectroscopy to verify ligand environments.
- Elemental analysis to confirm stoichiometry.
Stability studies demonstrate that the compound retains its structural integrity for at least 12 months when stored at 4 °C in the dark, provided that moisture is excluded.
Applications
Catalysis
Ed63a010 has been employed as a catalyst in several cross‑coupling reactions, including Suzuki–Miyaura and Heck reactions. Its high turnover numbers (TON) and turnover frequencies (TOF) are attributed to the stability of the ruthenium center and the flexible coordination sphere. In particular, the complex catalyzes the coupling of aryl halides with arylboronic acids under mild conditions, achieving yields exceeding 95% in many cases.
The catalyst is also effective in alkene hydration reactions, where it facilitates the addition of water across double bonds in the presence of phosphine ligands. The reaction proceeds with good regioselectivity and under relatively low catalyst loadings (≤ 0.5 mol % of Ed63a010).
Materials Science
In the field of materials science, Ed63a010 has been incorporated into metal–organic frameworks (MOFs) to introduce catalytic sites within porous matrices. The resulting MOF composites exhibit enhanced catalytic performance in gas‑phase oxidation reactions. Additionally, the complex has been used to modify electrode surfaces for electrocatalytic applications, improving electron transfer rates and lowering overpotentials in fuel cell technologies.
Medicinal Chemistry
Preliminary investigations into the potential of Ed63a010 as a metal‑based imaging agent have shown promising results. The complex can be radiolabeled with isotopes such as ^99mTc, and its biodistribution profile in animal models indicates preferential accumulation in certain tissues. However, further studies are required to evaluate toxicity, clearance rates, and long‑term safety.
Supramolecular Chemistry
Due to its ability to form robust coordination networks, Ed63a010 has been employed as a building block for supramolecular assemblies. The complex can self‑assemble into one‑dimensional chains or two‑dimensional layers, depending on the solvent and ligand concentration. These assemblies exhibit unique mechanical properties, such as flexibility and self‑repairing behavior, which have implications for the design of adaptive materials.
Regulatory Status
Chemical Safety Classification
Ed63a010 is classified under the Globally Harmonized System (GHS) as a Category 4 toxicant. The primary hazards include potential skin and eye irritation, and acute toxicity upon ingestion or inhalation. Safety data sheets (SDS) recommend standard protective equipment, including gloves, goggles, and respirators when handling the compound in powder form.
Environmental Impact
Environmental assessment studies indicate that Ed63a010 is moderately persistent in aqueous environments, with a half‑life of approximately 12 days at neutral pH. The compound exhibits low bioaccumulation potential in aquatic organisms. Nonetheless, measures to minimize releases into wastewater streams are advised, and authorized disposal methods include incineration at temperatures above 600 °C to ensure complete mineralization.
Regulatory Filings
In the United States, Ed63a010 has been submitted to the Environmental Protection Agency (EPA) under the Toxic Substances Control Act (TSCA) for evaluation. The compound is listed in the TSCA Inventory, and its commercial use is subject to licensing requirements. Similar regulatory frameworks exist in the European Union under the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) program, with the compound classified as a substance of very high concern (SVHC) due to its potential for endocrine disruption.
Safety and Environmental Impact
Handling Precautions
When preparing or using Ed63a010, laboratory personnel should wear appropriate personal protective equipment (PPE). The compound should be handled in a fume hood to prevent inhalation of dust or vapors. In case of skin contact, immediate rinsing with water and medical evaluation are recommended. Eye exposure requires thorough irrigation and professional medical assessment.
Fire and Explosion Hazard
Ed63a010 is not considered flammable in its solid state. However, its volatile organic solvent solutions can present flammability risks. The compound should be stored away from ignition sources, and solvent mixtures containing Ed63a010 should be kept in fire‑resistant containers.
Environmental Persistence
Studies on the degradation of Ed63a010 in environmental matrices suggest that photolysis and biodegradation processes lead to the breakdown of the phosphine ligands, producing phosphonate byproducts that are generally non‑toxic at environmentally relevant concentrations. The ruthenium core, however, persists longer and may accumulate in sediment layers under certain conditions. Monitoring programs in aquatic ecosystems have detected trace levels of the complex in regions adjacent to industrial facilities that employ Ed63a010 in catalytic processes.
Human Health Effects
Acute exposure to Ed63a010 can result in irritation of the skin and mucous membranes. Chronic exposure scenarios, such as prolonged inhalation of fine dust particles, have been associated with respiratory discomfort and potential neurotoxic effects. The compound has been flagged as a possible endocrine disruptor, and ongoing research is focused on delineating its mechanistic pathways in hormonal regulation.
Future Perspectives
Improved Catalyst Design
Efforts to enhance the catalytic efficiency of Ed63a010 involve modifying the phosphine ligand backbone to increase electron density at the ruthenium center. Substitutions with electron‑donating phenyl groups have shown incremental improvements in TOF values. Computational modeling suggests that steric hindrance from bulky substituents can be tuned to favor specific reaction pathways, opening avenues for selective catalysis in complex organic syntheses.
Integration into Photocatalytic Systems
Integrating Ed63a010 into photocatalytic platforms, such as TiO_2 films, may allow for dual catalytic action under visible light illumination. The ruthenium center can participate in photo‑excited electron transfer, while the phosphine ligands modulate the light absorption spectrum, potentially broadening the operational wavelength range.
Biodegradation Pathways
Biodegradation of Ed63a010 by soil microorganisms has been documented in controlled laboratory settings. Key enzymatic pathways involve the oxidation of phosphine ligands to phosphonates, followed by further oxidation to orthophosphate. The ruthenium center remains intact, but the complex can be sequestered by natural proteins, mitigating its toxicity. Future research aims to identify specific microbial strains capable of complete mineralization of both ligand and metal components.
Potential for Sustainable Catalysis
One of the main advantages of Ed63a010 lies in its reusability. In many catalytic processes, the complex can be recovered by simple precipitation or solvent extraction and reused without significant loss of activity. This attribute aligns with the principles of green chemistry, particularly the reduction of waste generation and the minimization of resource consumption.
Conclusion
Ed63a010 is a multifaceted organometallic complex that has found applications across catalysis, materials science, and emerging biomedical fields. Its synthesis, both industrial and laboratory, is well‑established, and quality control ensures high purity and stability. The complex's versatile coordination chemistry underpins its catalytic prowess, while its role in advanced materials and potential imaging applications offers exciting future directions. Regulatory oversight and safety guidelines emphasize responsible handling and environmental stewardship, ensuring that the benefits of Ed63a010 are balanced against potential health and ecological risks. Continued research into its mechanistic behavior, safety profile, and sustainable production will further expand its utility across scientific disciplines.
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