Chemistry of compounds with at least one metal-carbon bond. Straddles coordination and organic chemistry; underpins homogeneous catalysis (Grubbs, Suzuki, hydrogenation) and synthetic reagents like Grignards and organolithiums.
organometallic-chemistry
Grignard reagent structure
Organomagnesium halide RMgX (X = Cl, Br, I) prepared by direct insertion of Mg(0) into an alkyl or aryl halide in dry ether. In solution…
18-electron rule
Transition-metal complexes in which the valence shell (metal d + ligand donor orbitals) totals 18 electrons tend to be particularly stable,…
Ferrocene structure
Fe(C₅H₅)₂ — an iron(II) sandwiched between two parallel cyclopentadienyl (Cp⁻) rings. Each Cp donates 6 π electrons (η⁵ binding); together…
Oxidative addition
Elementary step in organometallic catalysis in which a low-valent metal centre inserts into an X–Y bond, increasing its formal oxidation…
Migratory insertion
Intramolecular migration of a σ-bonded ligand (H, alkyl, aryl) to an adjacent π-bonded ligand (CO, alkene, alkyne), forming a new bond and…
Pd-catalyzed cross-coupling
Suzuki (ArB(OH)₂), Negishi (RZnX), Kumada (RMgX), Stille (RSnR₃), Heck (alkene), Sonogashira (alkyne). General C-C bond formation.…
Olefin metathesis (Grubbs)
Ru/Mo carbene catalysts scramble alkene partners via [2+2] metallacyclobutane. Grubbs G1/G2/G3, Hoveyda-Grubbs, Schrock. Nobel 2005.
Reductive elimination
Reverse of oxidative addition: Mⁿ⁺²(R)(R') → Mⁿ + R-R'. Turnover-limiting for many cross-couplings. cis-geometry required; accelerated by…
C-H activation
Direct functionalization of unactivated C-H bonds via metal insertion. Directing groups (pyridyl, amide) steer selectivity. Pd/Rh/Ir/Ru.…
Metallocenes & Cp chemistry
Ferrocene (bis-cyclopentadienyl-Fe) discovered 1951; kicked off organometallic chemistry. Zirconocenes (Cp₂ZrCl₂) + MAO as single-site…
Oxidative addition & reductive elimination
M(n) + A-B → M(n+2)(A)(B); 3-center concerted (H₂) or SN2 (CH₃X); RE reverses; central to cross-coupling.
β-hydride elimination
σ-bond metathesis; M-CH₂CH₃ → M-H + CH₂=CH₂; requires empty site + syn-periplanar H; suppressed by blocking.
σ-bond metathesis
4-center concerted exchange of σ bonds at d⁰ metals (Sc, lanthanides); C-H activation of alkanes.
Olefin metathesis (Chauvin mechanism)
Metal-carbene + alkene → metallacyclobutane → new alkene + carbene; Grubbs Ru, Schrock Mo catalysts.
Hydroformylation / oxo process
RCH=CH₂ + CO + H₂ → RCH(CHO)CH₃ or RCH₂CH₂CHO; Co or Rh catalysts; n/iso selectivity; 10 Mt/yr scale.
Tolman cone angle & steric parameters
θ quantifies ligand sterics (PMe₃ 118°, PPh₃ 145°, PtBu₃ 182°); ν_CO electronic; Tolman maps.