Synthesis and characterization of iron(2+) and ruthenium(2+) diimino-, diamino- and diamido-diphosphine complexes. X-ray crystal structure of trans-RuCl₂(P₂N₂C₂H₄) · CHCl₃

The interaction of Ru(OAc)2(Ph3P)2with one equivalent of N,N′-bis[o-(diphenylphosphino)benzylidene]ethylenediamine (P2N2C2) in refluxing dichloromethane gave trans-Ru(OAc)2(P2N2C2) · 2H2O (I) in moderate yield (63%) ; in refluxing-toluene, it gave a red solid which upon recrystallization in CHCl3gave trans-RuCl2(P2N2C2) · 2H2O (II) in good yield (92%). Compound II could also be prepared in good yield (85%) via the interaction of RuCl2(DMSO)4with one equivalent of P2N2C2in refluxing toluene. The interaction of RuCl2(DMSO)4with one equivalent of N,N′-bis[o-(diphenylphosphino) benzylidene]-1,3-diaminopropane (P2N2C3), N,N′-bis[o-(diphenylphosphino)benzyl] ethylenediamine (P2N2C2H4) and N,N′-bis[o-(diphenylphosphino)benzamido]ethane (P2N2C2-amide) in refluxing toluene gave trans-RuCl2(P2N2C3) (III), trans-RuCl2(P2N2C2H4) (IV) and trans-RuCl2(P2N2C2-amide) (V) in good yield, respectively. The interaction of Fe(ClO4)2· 6H2O with one equivalent of P2N2C2and P2N2C2H4in refluxing acetonitrile gave trans-[Fe(P2N2C2)(CH3CN)2](ClO4)2(VI) and trans-[Fe(P2N2C2H4) (CH3CN)2](ClO4)2(VII), respectively. Interaction of FeCl2· 4H2O with one equivalent of N,N′-bis[o-(diphenylphosphino)benzylidene]-1,6-diaminohexane (P2N2C6) in refluxing gave trans-FeCl2(P2N2C6) (VIII). Complexes I-VIII have been fully characterized by analytical and spectroscopic methods. The structure of IV has been established by an X-ray diffraction study. Compound II could be reduced to compound IV with NaBH4in ethanol and oxidized to V with aqueous H2O2acetonitrile. Catalytic studies showed that both II and IV were effected catalysts for the hydrogenation of acrylic acid to propionic acid.