Atom-Transfer-Chain ATC Catalysis

3 Atom-Transfer-Chain (ATC) Catalysis 3.2.8.3.1 Halogen-ATC Catalysis 

The particle transferred in the chain reaction is now a hydrogen or a halogen atom rather than simply one electron. The cross atom-transfer propagation step is exer- 

Many classical reactions have been recognized to proceed according to this halogen-ATC catalysis mechanism examples are the dehydroiodination of secondary iodides by Pt° [10], the bromination of [Mn2(CO)io], and the exchange of carbonyls by phosphines or isonitriles [50]. 

This mechanism is quite general for this substitution reaction in transition metal hydride-carbonyl complexes [52]. It is also known for intramolecular oxidative addition of a C-H bond [53], heterobimetallic elimination of methane [54], insertion of olefins [55], silylenes [56], and CO [57] into M-H bonds, extmsion of CO from metal-formyl complexes [11] and coenzyme B12- dependent rearrangements [58]. Likewise, the reduction of alkyl halides by metal hydrides often proceeds according to the ATC mechanism with both H-atom and halogen-atom transfer in the propagation steps [4, 53]. 

Finally, group-transfer chain catalysis involves the transfer of a group in the cross-propagation step a few examples are known with transfers of groups such as allyl [59], cyclopentadienyl [60], and rhodium octaethylporphyrin [57]. 

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Besides ETC catalysis, atom-transfer chain (ATC) catalysis has been reviewed [2]. The initiation involves radicals and the redox propagation step exchanges an... 

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