Syntheses and structures of calcium and ytterbium bis(diphosphanylamido) complexes

Bis(diphosphanylamido) complexes of calcium and ytterbium, [{(Ph2P)2N}2M(THF)3] (M = Ca (1), Yb (2)), have been prepared by reaction of [K(THF)nN(PPh2)2] (n = 1.25, 1.5) and MI2. The single crystal X-ray structures of compounds 1 and 2 always show a η2-coordination of the ligand via the nitrogen and one phosphorus atom. In solution a dynamic behavior of the ligand is observed, which is caused by the rapid exchange of the two different phosphorus atoms.