SOLUBLE MONO(PENTAMETHYLCYCLOPENTADIENYL)ZIRCONIUM HYDRIDES - X-RAY STRUCTURE OF (C5ME5)2ZR2(MU-H)3CL3(PME3)

The 14-electron alkyl complex Cp*Zr[(CH2)3NMe2]Cl2 (Cp* = η5C5Me5), containing a chelating (dimethylamino)propyl ligand, reacts with H2 to form a soluble crystallizable mono-Cp* zirconium hydride with a complicated stoichiometry, tentatively formulated as “Cp*3Zr3H4Cl5”. Reaction of this compound with PMe3 induces disproportionation, in which Cp*ZrCl3(PMe3) and Cp*2Zr2(μ-H)3Cl3(PMe3), the first early-transition-metal (μ-H)3-bridged dimer, are formed. An X-ray structure determination of this compound (space group P21/c, a = 15.599 (3) A, b = 11.203 (3) A, c = 16.862 (4) A, β = 103.27 (2)° at 130 K, Z = 4) showed that one Cp*ZrCl(PMe3)- and one Cp*ZrCl2- moiety are bridged by three hydride ligands, with Zr-H distances ranging from 1.92 (3) to 2.35 (5) A and Zr-H-Zr angles from 85.9 (17) to 104.1 (19)°.