The dual nature of donor ligands is explored in Oxygen Atom Transfer (OAT) in this hot article by Adam Veige and co-workers. In this study, donor ligands enhance the rate of OAT by hindering µ-O dimer formation; however, the addition of a too strongly coordinating ligand can actually prevent OAT by
making the transfer thermodynamically unfavorable.
Read more about this ligand duality for FREE until 13th December 2012:
The influence of reversible trianionic pincer OCO3– µ-oxo CrIV dimer formation ([CrIV]2(µ-O)) and donor ligands in oxygen-atom-transfer (OAT)
Matthew E. O’Reilly, Trevor J. Del Castillo, Khalil A. Abboud and Adam S. Veige
Dalton Trans., 2012, Advance Article