DIMERIC NAPHTHYL HYDRIDE DERIVATIVE OF ZIRCONOCENE - SYNTHESIS, STRUCTURE, AND CHEMICAL PROPERTIES

Reduction of bis(η-cyclopentadienyl)zirconium dichloride with potassium naphthalene, at low temperatures in tetra-hydrofuran, yields μ-(2-η1;:1-2-η2-naphthyl)-hydrido-bis[bis(η-cyclopentadienyl)zirconium] (Zr-Zr), (η-C5H5)2-Zr(C10H7)(H)Zr(η-C5H5)2 (hereinafter labeled I). The compound was characterized by a combination of chemical methods and X-ray crystallography. Crystals of I are orthorhombic, of space group Pbca (centrosymmetric), cell parameters a = 1.9243 (8), b = 2.0507 (6), and c = 1.1931 (8) nm, and contain eight molecules of (C5H5)4Zr2(C10H7)(H) per unit cell. Key structural parameters follow: D(Zr-Zr) = 0.3307 (2), mean D(Zr-C5H5, centroid) = 0.255 (3), D(Zr-η1-naphthyl, carbon) = 0.229 (1) nm. The hydrido ligand in I was not located by the X-ray work, but its presence was inferred from 1NMR spectra in THF-d8, which show a singlet at δ(CH-9.3. Reaction of I with excess CH3I yields 1 mol CH4/Zr2 unit, which is in accordance with the monohydride structure. With HCl in THF, dicyclopentadienylzirconium dichloride, hydrogen, naphthalene, and a mixture of partially hydrogenated and hydrochlorinated naphthalenes are formed. Reaction of the complex with H2 in THF yields naphthalene and dicyclopentadienylzirconium dihydride. In toluene and THF solutions, I is a catalyst for the hydrogenation of cyclohexene to cyclohexane. © 1979, American Chemical Society. All rights reserved.