Crystal and molecular structure of a σ-phenyl complex of nickel: (π-C5H5)Ni(PPh3)Ph

Abstract

π-Cyclopentadienyl(triphenylphosphine)-σ-phenylnickel, (π-C₅H₅)Ni(PPh₃)Ph, crystallizes in the monoclinic spacegroup B2₁/c(C_2h⁵; no, 14) with a= 27·42 ± 0·03, b= 9·49 ± 0·01, c= 18·25 ± 0·02 Å, β= 102·46°± 0·04°, and Z= 8. A three-dimensional single-crystal X-ray structural analysis, based on data in the range 8°⩽ 2θ⩽ 46°(Mo-K_α radiation) collected with a Buerger automated diffractometer, has led to the location of all 31 non-hydrogen atoms. The structure was solved by conventional Patterson, Fourier and least-squares refinement procedures, the final R being 7·5% for 2424 independent, non-zero reflections. The crystal is composed of distinct molecular units of (π-C₅H₅)Ni(PPh₃)Ph, separated by normal van der Waals' forces. The nickel atom is in a pseudo-pentaco-ordinate environment, being bonded to a triphenylphosphine, a σ-phenyl and a formally tridentate π-cyclopentadienyl ligand. The nickel–phosphorus distance is 2·138 (σ 0·002)Å, the nickel–phenyl bond-length, Ni–C(1), is 1·904 (σ 0·007)Å, and the angle P–Ni–C(1) is 93·4 (σ 0·2)°. As expected, all aromatic systems are planar within experimental error, but the internal angle of the σ-phenyl group at C(1) is only 115·9°, significantly (5·8 σ) lower than the normal sp² angle. The molecular geometry is discussed with particular reference to the analogous perfluorophenyl complex, (π-C₅H₅)Ni(PPh₃)C₆F₅.