Transforming P4: The reaction of the anionic Cp*Fe− equivalent 1 with white phosphorus is a promising new approach toward P4 activation. The reaction proceeded under mild conditions and enabled the synthesis of remarkable anionic polyphosphido complexes. Two new iron polyphosphides 2 and 3 were isolated and characterized by X-ray crystallography, 31P NMR spectroscopy, and quantum chemical calculations.