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

Article abstract of DOI:10.1016/0277-5387(95)00385-1

The interaction of Ru(OAc)₂(Ph₃P)₂ with 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 CHCl₃ gave 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)₄ with one equivalent of P₂N₂C₂ in refluxing toluene. The interaction of RuCl₂(DMSO)₄ with 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 P₂N₂C₂ and P₂N₂C₂H₄ in 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 NaBH₄ in ethanol and oxidized to V with aqueous H₂O₂ acetonitrile. Catalytic studies showed that both II and IV were effected catalysts for the hydrogenation of acrylic acid to propionic acid.