Organometallic chemistry Insertion reaction

1 organometallic chemistry

1.1 carbonylations
1.2 olefin insertion
1.3 other insertion reactions in coordination chemistry

organometallic chemistry

many reactions in organometallic chemistry involve insertion of 1 ligand (l) metal-hydride or metal-alkyl/aryl bond. hydride, alkyl, or aryl group migrates onto l, co, alkene, or alkyne.

carbonylations

the insertion of carbon monoxide , alkenes metal-carbon bonds exploited reaction major industrial applications.

nucleophilic insertion , rearrangement of square planar complex

such reactions subject usual parameters affect other reactions in coordination chemistry, steric effects important in determining stereochemistry , regiochemistry of reactions. reverse reaction, de-insertion of co , alkenes, of fundamental significance in many catalytic cycles well.

widely employed applications of migratory insertion of carbonyl groups hydroformylation , carbonylative production of acetic acid. former converts alkenes, hydrogen, , carbon monoxide aldehydes. production of acetic acid carbonylation proceeds via 2 similar industrial processes. more traditional rhodium-based monsanto acetic acid process, process has been superseded iridium-based cativa process. 2002, worldwide annual production of acetic acid stood @ 6 million tons, of approximately 60% produced cativa process.

the cativa process catalytic cycle, shown above, includes both insertion , de-insertion steps. oxidative addition reaction of methyl iodide (1) involves formal insertion of iridium(i) centre carbon-iodine bond, whereas step (3) (4) example of migratory insertion of carbon monoxide iridium-carbon bond. active catalyst species regenerated reductive elimination of acetyl iodide (4), de-insertion reaction.

olefin insertion

the insertion of ethylene , propylene titanium alkyls cornerstone of ziegler-natta catalysis, commercial route of polyethylene , polypropylene. technology involves heterogeneous catalysts, assumed principles , observations on homogeneous systems applicable solid-state versions. related technologies include shell higher olefin process produces detergent precursors. olefin can coordinated metal before insertion. depending on ligand density of metal, ligand dissociation may necessary provide coordination site olefin.

migratory insertion of alkene metal hydride. middle image depicts transition state. notice less substituted carbon becomes bonded metal, @ least usually. reverse reaction called beta-hydride elimination.



other insertion reactions in coordination chemistry

many electrophilic oxides insert metal carbon bonds; these include sulfur dioxide, carbon dioxide, , nitric oxide. these reactions have limited practical significance, of historic interest. transition metal alkyls, these oxides behave electrophiles , insert bond between metals , relatively nucleophilic alkyl ligands. discussed in article on metal sulfur dioxide complexes, insertion of so2 has been examined in particular detail.