Bonding halogen atom

Dehalogenation can occur by several reductive pathways. The simplest results in replacement of a C-bonded halogen atom with a hydrogen and is known as hydrogenolysis or reductive dehalogenation. The process is illustrated for trichloroethene, TCE,... 

Hydrogenation. The iron complex 1 is a highly selective hydrogenation catalyst for reducing the carbonyl group. Double bond, triple bond, halogen atoms, cyclopropane and pyridine rings are not affected. 

Figure 2.45 Directionality in H-bonds to metal-bonded halogen atoms (X-H...CI-M).

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