After having demonstrated that cyclo-P5 could be stabilized as bridging ligand in the mixed-valence triple-decker complex 1, ('71 we then attempted to realize the classical sandwich coordination of this ligand (cyclo-Py as 6x electron donor). Success was achieved upon cothermolysis of 2 with white phosphorus.Pentamethylpentaphosphaferrocene 3 forms sublimable, green crystals which can be handled in the presence of air and which begin to melt (with partial sublimation and slight decomposition) at 270°C when heated in a sealed tube. 3 is very soluble in dichloromethane, readily soluble in benzene and toluene, and moderately soluble in pentane. [**I This work was supported by the Fonds der Chemischen Industrie trum,'21 the most intense peak is the molecular peak of 3, followed by the peak for M@-P2. 10.6 (s; CH,); 4 : 6=78.5 (s; C5Mes), 9.8 (s; CH,). El-MS (70 ev) of 3 : m / z 346 (Ma, I,,,= 100%), 284 ( M a -Pz, 91%), P, (19.8%), P, (7.9%). P2 (53%), P (7.8%) and further, weak Intensity lines. We have now found that reaction of [Fe,(CO),,] 1 with (Me,Si),N-P=NSiMe3 2 not only leads to formation of the unusual tridentate 6e-donor ligand B (stabilized in the cluster 3) but also gives the phosphanediyl (phosphini-
