Iron- and ruthenium-containing triple-decker complexes with a central pentaphospholyl ligand -: X-ray structures of [(η-C5H5)Fe(μ-η:η-P5)Ru(η-C5Me5)]PF6 and [(η-C5Me5)Ru(μ-η:η-P5)Ru(η-C5Me5)]PF6

Triple-decker cationic complexes with a central pentaphospholyl (pentaphosphacyclopentadienyl) ligand [Cp.M(mu-eta:eta-P-5)M'(eta-C5R5)](+) (3b: M = M' = Fe, R = Me; 4a: M = Ru, M' = Fe, R = H; 4b: M = Fe, M' = Ru, R = H; 4c: M = Fe, M' = Ru, R = Me; 5a: M = M' = Ru, R = H; 5b: M = M' = Ru, R = Me) were synthesized by exploitation of the stacking reactions of pentaphosphametallocenes Cp.M(eta-P-5) (1: M = Fe; 2: M = Ru) with half-sandwich fragments [(eta-C5R5)M'](+). They were isolated as salts with BF4- or PF6- anions, and the structures of 4aPF(6) and 5bPF(6) were determined by X-ray diffraction. Triple-decker complexes with a central pentaphospholyl ligand are less reactive in nucleophilic degradation reactions than analogous complexes with C4Me4P and Cp. ligands in the bridging position. Only 4a and the previously known analogue 3a (M = M' = Fe, R = H), containing the CpFe fragment, are nucleophilically destroyed by MeCN and NaI. The electrochemical properties of 2, 3a, 3b, 4a-c, 5a and 5b and the related cobalt-containing complexes [(eta-C4Me4)Co(mu-eta: eta-P-5)MCp.](+) (6: M = Fe; 7: M = Ru) were investigated. g ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).