PHD
  1. Inorganic chemistry  1.1. Coordination chemistry  1.1.1. Ligand field theory  1.1.2. Crystal field theory  1.1.3. Molecular Orbital Theory for Coordination Compounds  1.1.4. Stability of Coordination Compounds  1.1.5. Electronic spectra of coordination compounds  1.1.6. Isomerism in Coordination Compounds  1.1.7. Kinetics and mechanism of coordination reactions  1.2. Organometallic Chemistry  1.2.1. Metal Carbonyls  1.2.2. Metal alkyl and aryl  1.2.3. Fischer and Schrock carbonaceans  1.2.4. Oxidative Addition and Reductive Elimination  1.2.5. Metal Hydrides  1.2.6. Catalysis by organometallic compounds  1.2.7. Metallocenes and Sandwich Complexes  1.2.8. CH activation  1.3. Solid state chemistry  1.3.1. Crystal structures and lattices  1.3.2. Band theory and electrical properties  1.3.3. Defects in the crystal  1.3.4. Synthesis of solid state materials  1.3.5. Magnetic and optical properties of solids  1.3.6. Superconductivity  1.3.7. Solid state ionics  1.4. Bio-inorganic chemistry  1.4.1. Metalloproteins and enzymes  1.4.2. Metal ion transport and storage  1.4.3. The role of metals in medicine  1.4.4. Bioinspired catalysis  1.4.5. Metal–DNA interactions  1.4.6. Metal Complexes in Medical Science  1.5. Lanthanides and Actinides  1.5.1. Electronic configuration and oxidation states in lanthanides and actinides  1.5.2. Spectral and Magnetic Properties in Lanthanides and Actinides  1.5.3. Separation and Extraction of Lanthanides and Actinides  1.5.4. Coordination chemistry of f-block elements  1.6. Main Group Chemistry  1.6.1. Chemistry of boron compounds  1.6.2. Chemistry of Silicon and Germanium Compounds  1.6.3. Chemistry of Phosphorus and Sulfur Compounds  1.6.4. Organosilicon chemistry  1.6.5. Noble Gas Chemistry
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition and substitution reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic Reactions  2.1.7. Photochemical reactions  2.2. Stereoscopic  2.2.1. Chirality and optical activity  2.2.2. Structural analysis  2.2.3. Stereoelectronic effects  2.2.4. Asymmetric synthesis  2.2.5. Dynamic Stereochemistry  2.3. Organometallic Chemistry in Organic Synthesis  2.3.1. Organolithium and organomagnesium reagents  2.3.2. Transition metal catalyzed coupling reactions  2.3.3. Palladium-catalyzed reactions  2.3.4. Olefin Metathesis  2.3.5. Gold and silver catalysis  2.4. Natural products chemistry  2.4.1. Alkaloids and terpenoids  2.4.2. Steroids and Flavonoids  2.4.3. Total synthesis of natural products  2.4.4. Biosynthesis of natural products  2.5. Supramolecular Chemistry  2.5.1. Host-Guest Chemistry  2.5.2. Self-assembly and molecular recognition  2.5.3. Supramolecular Catalysis  2.5.4. Molecular Machines
  3. Physical Chemistry  3.1. Thermodynamics  3.1.1. Laws of Thermodynamics  3.1.2. Chemical Potential and Equilibrium  3.1.3. Statistical thermodynamics  3.1.4. Non-equilibrium thermodynamics  3.2. Quantum Chemistry  3.2.1. Schrödinger equation and its applications  3.2.2. Molecular orbital theory  3.2.3. Density functional theory  3.2.4. Post-Hartree–Fock methods  3.3. Chemical kinetics  3.3.1. Reaction rate theory  3.3.2. Mechanism and rate laws  3.3.3. Catalysis and enzyme kinetics  3.3.4. Reaction dynamics  3.4. Spectroscopy and molecular structure  3.4.1. Infrared Spectroscopy  3.4.2. UV-visible spectroscopy  3.4.3. Nuclear Magnetic Resonance Spectroscopy  3.4.4. Mass Spectrometry  3.4.5. Raman Spectroscopy  3.5. Surface and Colloid Chemistry  3.5.1. Absorption and Catalysis  3.5.2. Surfactants and micelles  3.5.3. Colloidal Stability  3.5.4. Nanomaterials and Interfaces
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.1.4. Ion Chromatography  4.2. Electroanalytical techniques  4.2.1. Voltammetry and Polarography  4.2.2. Conductometry and potentiometry  4.2.3. Colometry  4.3. Spectroscopic Methods  4.3.1. Atomic absorption spectroscopy  4.3.2. Fluorescence Spectroscopy  4.3.3. X-ray diffraction  4.3.4. Electron paramagnetic resonance spectroscopy  4.4. Chemometrics  4.4.1. Data processing and statistical methods  4.4.2. Multidisciplinary analysis  4.4.3. Machine Learning in Analytical Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.2. Quantum chemistry methods  5.3. Computational drug design  5.4. Machine Learning in Chemistry  5.5. Ab initio molecular dynamics
  6. Biophysics and Medicinal Chemistry  6.1. Drug discovery and design  6.2. Enzyme kinetics and inhibition  6.3. Chemical biology approach  6.4. Protein-ligand interactions  6.5. Bioorthogonal chemistry
  7. Materials chemistry  7.1. Polymer chemistry  7.1.1. Polymerization mechanism  7.1.2. Functional Polymers  7.1.3. Biodegradable Polymer  7.1.4. Conducting and semiconducting polymers  7.2. Nano Chemistry  7.2.1. Nanoparticles and nanostructures  7.2.2. Carbon-based nanomaterials  7.2.3. Quantum dots  7.3. Energy and Environmental Chemistry  7.3.1. Battery and Fuel Cell Chemistry  7.3.2. Green chemistry and sustainable materials  7.3.3. Photocatalysis

PHD → Inorganic chemistry → Organometallic Chemistry ↓


Oxidative Addition and Reductive Elimination


Organometallic chemistry is a fascinating field that bridges the gap between organic chemistry and inorganic chemistry, focusing particularly on compounds containing at least one metal-to-carbon bond. Of the many reactions in organometallic chemistry, oxidative addition and reductive elimination are two of the most fundamental and frequently encountered processes. These reactions are important in catalytic cycles of various mechanisms, including cross-coupling reactions used in industrial applications.

Oxidative additives

Oxidative addition is a process in which a metal complex increases its oxidation state by two units as it forms bonds with the added ligand. Generally, this involves the insertion of a metal into a covalent bond (usually HH, CH, CX, etc.). It is a key step in many organometallic catalytic cycles, including those involving palladium, platinum, rhodium, and iridium complexes.

General mechanism

The general equation for oxidative addition can be represented as:

LnM + XY → LnM(X)(Y)

Here, LnM represents a metal complex with a group of ligand L coordinated to the metal M, and XY is a bond in a molecule that undergoes oxidative addition.

Kinetic and thermodynamic aspects

Kinetically, for oxidative addition to occur, the metal center must be coordinatively unsaturated or at least have accessible empty orbitals. Thermodynamically, the reaction is favored when the formation of two new metal-ligand bonds energetically compensates for the breaking of XY bond.

Examples of oxidative summation

Consider a classic example with a square planar palladium(0) complex:

Pd(PPh₃)₄ + CH₃I → I-Pd(PPh₃)₂-CH₃

In this example, iodide (I⁻) and methyl (CH₃³⁺) are added to the Pd(0) complex, resulting in a Pd(II) complex.

Visual example

P.D. I CH₃

This SVG diagram shows the oxidative addition of CH₃I to Pd(PPh₃)₄.

Reductive elimination

Reductive elimination is the opposite process of oxidative addition. It involves the removal of a pair of ligands from the metal center, thereby reducing the oxidation state of the metal by two units. This process is important for the completion of catalytic cycles by releasing the organic product(s).

General mechanism

The general equation for catabolic elimination can be written as:

LnM(X)(Y) → LnM + XY

Here, LnM(X)(Y) is a complex that removes XY fragment, restoring the metal to its lower oxidation state.

Kinetic and thermodynamic aspects

For reductive elimination to be favorable, the ligands X and Y must be cis to each other at the metal center, allowing them to bind and release as a unit. Thermodynamically, this process is more favorable if the resulting XY bond is strong, which compensates for the energy needed to break the metal-ligand bond.

Examples of reductive elimination

Consider the reductive elimination from a palladium(II) complex:

I-Pd(PPh₃)₂-CH₃ → Pd(PPh₃)₂ + CH₃I

This reaction removes methyl iodide (CH₃I), resulting in the formation of a Pd(0) complex.

Visual example

P.D. I CH₃ PPH₃

This SVG diagram shows the reselective elimination of CH₃I from a palladium complex.

Catalytic cycles involving oxidative addition and reductive elimination

Many catalytic cycles needed in industrial chemistry, such as the Suzuki, Negishi and Stille coupling reactions, rely heavily on oxidative additions and reductive eliminations. These processes ensure the regeneration of the catalyst, allowing the cycle to continue.

Example: Suzuki coupling reaction

The Suzuki coupling is a powerful method of forming carbon-carbon bonds. This cycle usually involves the following steps:

  1. Oxidative addition of aryl or vinyl halides to a palladium(0) catalyst.
  2. Transmetalation with boronate esters.
  3. Reductive elimination, releasing the coupled product and regenerating the palladium(0) catalyst.

In this context, the oxidative addition and reductive elimination steps are important, which ensure the transfer of molecular fragments and the completion of the catalytic cycle.

Visual example of a Suzuki bicycle

Oxidative Additives Pd(0) + Ar-X → Pd(II)X-Ar Transmetalation Pd(II)X-Ar + B(OR)₂ → Pd(II)Ar-R + XB(OR)₂ Reductive Elimination Pd(II)Ar-R → Pd(0) + Ar-R

This SVG diagram shows the Suzuki coupling cycle, and highlights the roles of oxidative addition and reductive elimination.

Conclusion

Oxidative addition and reductive elimination are central processes in organometallic chemistry, facilitating catalytic transformations by mediating changes in oxidation state and coordinating new ligands to or from the metal center. Understanding these reactions not only allows chemists to design effective catalytic cycles, but also opens the door to creating new compounds with industrial and pharmaceutical applications.

In summary, the interplay between oxidative addition and reductive elimination provides a dynamic mechanism for manipulating chemical bonds, underscoring the versatility and utility of organometallic chemistry.


PHD → 1.2.4


U
username
0%
completed in PHD

← Prev (1.2.3)
Fischer and Schrock carbonaceans
Next (1.2.5) →
Metal Hydrides

Comments 



Oxidative Addition and Reductive Elimination

https://www.chemistryelite.com/phd/1.2.4?ceal=en