Chemistry for solar fuel
Electron transfer: Taube, Marcus
Multi-electron transfer: ??? (proton coupled electron transfer)
Lewis N S , Nocera D G PNAS 2006;103:15729-15735
©2006 by National Academy of Sciences
.
Lewis N S , Nocera D G PNAS 2006;103:15729-15735
©2006 by National Academy of Sciences
.
Attacco nucleofilo: O2- (8e) + O2+ (4e)
[4e: multimetal centres?]
Lewis N S , Nocera D G PNAS 2006;103:15729-15735
©2006 by National Academy of Sciences
.
Radical coupling O (6e) + O (6e)
Lewis N S , Nocera D G PNAS 2006;103:15729-15735
©2006 by National Academy of Sciences
.
Eliminazione riduttiva (4e change)
Lewis N S , Nocera D G PNAS 2006;103:15729-15735
©2006 by National Academy of Sciences
.
Eliminazione riduttiva (4e change)
Lewis N S , Nocera D G PNAS 2006;103:15729-15735
©2006 by National Academy of Sciences
Chemistry for solar fuel:
- multielectron transformation
- formation of high-energy bond (driven by energy input)
- proton coupled electron transfer
Electronic Excited states needed to drive formation of
high energy bonds
Multi-electron chemistry difficult
Multielectron redox chemistry
Disproportionation M(n+1)-M(n+1) = M(n+2)-M(n)
Two-electron steps reactivity
M = Mo(II), W(II)
Disproportionation favored by A-D-A ligands: two paccepting moieties with a p-donor bridgehead (amine
between two electron deficient ligands)
Bis(difluorophosphino)methylamine:
dfpma
Bis[bis(trifluoroethoxy)phosphino]
methylamine: tfepma
A-D-A complex: two-electron mixed valence
Metal- and Ligand-based mixed valency
Ligand-based two electron mixed valence complexes
Proton-coupled electron transfer
2H+ + 2e = H2; 0 V
H+ + e = H. ; 2.3 V