A quest for triple-decker complexes with a bridging phospholyl ligand. Syntheses of [(μ,η5:η5-C4Me4P)(FeCp∗)(RhCp∗)](BF4)2 and [(μ,η5:η5-C4Me4P)(FeCp∗)(IrCp∗)](BF4)2, and structures of [Cp∗Fe (μ,η1:η5-C4Me4P)Ir(NCMe)2Cp∗](CF3SO3)2(Me2CO) and (C5Me4CH2C6H1

The new triple-decker complexes [(μ,η5:η5-C4Me4P)(FeCp∗)(MCp∗)](BF4)2 (9:M=Rh; 10:M=Ir) are obtained from the phosphaferrocene Cp∗Fe(C4Me4P) (3a) by electrophilic stacking reactions in acetone. These stacking reactions are suppressed by the presence of even rather weak nucleophiles. In acetonitrile as solvent the σ-bonded complexes [Cp∗Fe(μ,η1:η5-C4Me4P)M(NCMe)2Cp∗] CF3SO3 (11:M=Rh; 12:M=Ir) are obtained, and Cp∗Fe(μ,η1:η5-C4Me4P)Rh(O3SCF3)2Cp∗ (14a) is formed when triflate ions are present in acetone. Nucleophilic degradation of 9 and 10 in acetone produces the corresponding sandwich complexes [Cp∗Rh(C4Me4P)]BF4 (15) (inter alia), and [Cp∗Ir(C4Me4P)]BF4 (16).