Transition metal photolabile complexes

Transition metal n-complexes can be used in photolabile linkers. The ir-complex 40 was formed from the chromium arene complex 39 and polymer-supported tri-phenylphosphine (38) [60] (Scheme 17.20). The complex 40 tolerated LiAlH4 reduction and acetylation, but released the product 41 in 70% yield when oxidized with air under the influence of UV irradiation. 

Scheme 17.20 Example of the use of a transition metal 71-complexes in photolabile linkers.

The photochemical formation of these complexes generally occurs from initial loss of CO or some similarly photolabile substituent from the transition metal centre. A common mode of attack of the Group 14 organometallic on the unsaturated species thus formed is by oxidative addition. There are many examples of such reactions, the most common involve E—H cleavage88 equations 40 and 41 show typical reactions. 

Transition-metal complexes of a-hydroxy acids can be photolabile. The oil-degrading marine bacterium Marinobacter hydrocarbonoclasticus produces a siderophore, which appears to exploit photodecarboxylation to facilitate iron release. Petrobactin (Figure 4) forms a stable ferric complex through iron chelation by two catecholate moieties and a citryl group. Decarboxylation of the citryl moiety via photolysis of ferric petrobactin yields a less stable ferric complex than the... 

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