Macrocyclic reducing agents

Copper(I) complexes can be generated by radical reduction of the corresponding Cu(II) complex. A few copper(I) macrocycles are remarkably stable but usually they are strong reducing agents reactive in O2, and disproportionate to copper(II) and metallic copper. 

Like other tetraaza metallo(I) complexes, the nickel(I) macrocyclic ions are powerful and labile reducing agents. A point of some interest in these systems is to design a complex couple for which the nickel(I) state is accessible at reasonable potentials. Provided the tetraaza macrocyclic ligand maintains close to planar microsymmetry, reorganizational barriers for a low-spin d8-d9 system might be expected to be small (194). 

Transannular amidomercuration of macrocyclic lactams leads to heterocyclic cyclohexyl mercury compounds, which contain an annulated cyclopentyl ring76. Reductive alkylation with 2-propenenitrile and reducing agents proceeds with stereoselective addition tram to the cyclopentyl ring. 

Macrocyclic complexes of transition metals are widely used as both oxidising and reducing agents as well as catalysts in many redox processes [17, 50-56], In particular, macrobicyclic complexes such as [Co(L824)] and related compounds appear to be effective electron carriers in the photocatalytic decomposition of water [57-63],... 

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