Stabilization of low-oxidation-state early transition-metal complexes bearing 1,2,4-triphosphacyclopentadienyl ligands: structure of [[Sc(P3C2tBu2)2]2]; ScII or mixed oxidation state?
Angew Chem Int Ed Engl. 2003 Mar 3;42(9):1038-41.
doi: 10.1002/anie.200390267.