TRANSITION-METAL-SUBSTITUTED DIPHOSPHENES .33. PREPARATION OF THE ETA-2-1,2-DIPHOSPHAALLYL COMPLEX (ETA-5-C5ME5)(CO)FEP(SIME3)P=C(SIME3)2 AND REACTION WITH NI(CO)4 AND PME3 - FORMATION OF THE ETA-3-FERRADIPHOSPHAALLYL COMPLEX [(ETA-5-C5ME5)(CO)(MU-CO)FEP=PC(SIME3)3]NI(CO)2

Irradiation of the eta1-1,2-diphosphaallyl complex (eta-C5Me5)(CO)2FeP(SiMe3)P=C(SiMe3)2 (1a) afforded the eta-diphosphaallyl complex(eta5-C5Me5)(CO)-FeP(SiMe3)P=C(SiMe3)2 (4) with liberation of 1 equiv of CO. Thermolabile 4 was characterized in solution by spectroscopic means (JR; H-1, C-13, P-31 NMR) and by selected chemical reactions. Treatment of 4 with Ni-(CO)4 led to regeneration of 1a, whereas the addition of PMe3 induced a rearrangement to give the metallo-diphosphene 8. 8 was converted by an excess of Ni(CO)4 to the complex [(eta5-C5Me5)(CO)(mu-CO)-FeP-PC(SiMe3)-3]Ni(CO)2 (9). Structures for 8 and 9 are proposed on the basis of spectroscopic data and elemental analyses.