Structures of hydrides formed by addition of an organic molecule to a transition-metal complex. Part I. Crystal and molecular structure of hydridobis-[1,2-bis(dimethylphosphino)ethane]naphthylruthenium(II) and its osmium analogue

Abstract

The system M⁰(naphthalene)(dmpe)₂⇌ M^IIH(naphthyl)(dmpe)₂, where M = Ru or Os and dmpe = Me₂P·CH₂·-CH₂·PMe₂, involves an equilibrium between a low-valent M⁰ complex and a hydridic higher-valent structure. The structures of the crystals obtained from this system have been determined for both M = Ru and M = Os showing that, in the solid state, these compounds are M^II naphthyl hydrides. The ruthenium and osmium complexes are isostructural (P2₁/c, Z= 4, a=ca. 15·3, b=ca. 18·7 Å, and β=ca. 114°). Diffractometer data have been refined to R= 0·080 and 0·072 (Ru and Os complexes respectively). The metal atom is approximately octahedrally co-ordinated with the hydridic hydrogen cis to the σ-bonded naphthyl group. The Ru–H distance is 1·7 Å; the M–P bond lengths range from 2·28 to 2·33 Å with the longer bonds trans to hydrogen. The two M–C bonds, Ru–C 2·16 and Os–C 2·13 Å, are longer than comparable M–C(aryl) bonds. Both phosphine ligands in each complex have disordered bridging methylene groups. The σ–π rearrangement in the equilibrium system is discussed in relation to the known structures of metal–arene complexes.