Reduction of ZrCl4 or HfCl4 with Na/K alloy in the presence of the chelating phosphine 1,2-bis(diisopropylphosphino)ethane (dippe) gives the metal-metal-bonded dimers Zr2Cl6(dippe)2 and Hf2Cl6(dippe)2. These dark green compounds are diamagnetic as opposed to the previously reported paramagnetic titanium(III) dimer Ti2Cl6(dippe)2. The hafnium compound is the first molecular hafnium(III) species of any kind to be crystallographically characterized. The dimer is composed of two octahedral hafnium centers that are connected by two bridging chloride ligands: the Hf-Hf bond length is 3.099 (1) Å. Overall, the structure closely resembles analogous zirconium(III) dimers that have been described previously. Other distances and angles in the molecule are Hf-P = 2.746 (5) Å, Hf-Clt = 2.408 (4) Å, Hf-Clb = 2.517 (4) Å, Hf-Clb-Hf = 76.0 (1)°, Cl.,-Hf-Cl., = 104.0 (1)°, Cl-Hf-Clt, = 166.5 (1)°, and P-Hf-P = 76.7 (1)°. Crystal data for Hf2Cl6(dippe)2.PhMe: orthorhombic, space group Pbcn, with a = 15.176 (2) Å, b = 14.503 (4) Å, c = 21.473 (4) Å, V= 4726 (4) Å3, Z = 4, RF = 0.046, and RwF = 0.053 for 179 variables and 1791 data with I > 2.58σ(I).
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry