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

Abstract

Triple-decker cationic complexes with a central pentaphospholyl (pentaphosphacyclopentadienyl) ligand [Cp*M(μ-η:η-P5)M′(η-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(η-P5) (1: M = Fe; 2: M = Ru) with half-sandwich fragments [(η-C5R5)M′]+. They were isolated as salts with BF4− or PF6− anions, and the structures of 4aPF6 and 5bPF6 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 [(η-C4Me4)Co(μ-η:η-P5)MCp*]+ (6: M = Fe; 7: M = Ru) were investigated. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)