Synthesis and X-ray structures of RuCpClL [L=(η1-PPh2py)2 and η2-triphos] and [RuCp{η3-(PPh2)3CH}][PF6]. The first η3-(PPh2)3CH complex of Ru(II)

Diphenyl-2-phosphinopyridyl (dppy) and 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) react with RuCpCl(COD), (COD=cycloocta-1,5-diene; Cp=η5-C5H5) by the displacement of the COD ligand to give, respectively, RuCpCl(η1-dppy)2 (I) and RuCpCl(η2-triphos) (II). When RuCpCl(PPh3)2 was used as the starting material, substitution of PPh3 ligands by dppy ligands afforded a mixture of di- (I) and mono-substituted RuCpCl(dppy)(PPh3) (III) complexes. The structure of (I) has been determined by X-ray crystallography and has been refined to a final R value of 0.0516. Both dppy ligands are P-coordinated. Crystal structure analysis of (II) shows that two phosphorus atoms are coordinated to the ruthenium atom in a chelating mode, and that the third phosphorus atom is free. This structure was refined successfully to a conventional R value of 0.0495. Reaction of RuCpCl(η2-tripod) {tripod=1,1,1-tris(triphenylphosphino)methane} with an excess of NH4PF6 gives the first η3-tripod ruthenium complex [RuCp(η3-tripod)][PF6] (IV) in 94% yield. The analogous triflate complex [RuCp(η3-tripod)][CF3SO3] (V) has also been prepared. Crystal structure analysis of complex (IV) shows that all three phosphorus atoms are coordinated to the ruthenium atom, and that all three PCP angles are less than 90°, leading to considerable strain in the tricyclic system. The structure was refined successfully to a conventional R value of 0.0538. Treatment of the triflate complex (V) with [(C4H9)4N][Rh(CO)2Cl2] gave the known complex CpRu(μ-CO)2(μ-Ph2PCH2PPh2)RhCl2 via a PC bond cleavage reaction.