Group migrations, acyl alkyl

In important recent work, Shriver has demonstrated that electrophiles can promote the migration of alkyl groups to coordinated CO. Lewis acid adducts of metal acyl complexes are isolated [37]. Thus it is possible that electrophilic species might also facilitate the generation of catalyst-bound formyls. 

The benzoyl derivative, PhCOMn(CO)5 and related acyl derivatives have intrinsic interest because they can be prepared by alkyl group migration to coordinated CO, a formal internal nucleophilic attack. This reaction, which is often referred to as carbonyl insertion86), is reversible in certain instances to give the metal alkyl. The enthalpy of disruption for PhCOMn(CO)s (Table 13) can be divided up to give the b.e.c of the Mn-COPh bond if the values of T (Mn-CO) shown in Table 13 are used, then the Mn-COPh enthalpy lies in the range 105 10 kJ mol-1, the lower value being preferred as outlined earlier. 

Acyl complexes can be formed from migration of alkyl groups to CO ligands, as in the following example. 

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