Synthesis and characterization of a mixed-ring bis-cyclopentadienyl derivative of neodymium.: X-ray crystal structures of (η-C5Me5)NdI2(py)3 and (η-C5Me5)(η-C5H4SiMe3)NdI(py)

Reaction of neodymium metal with 1.5 equiv of elemental iodine in iso-propanol, followed by crystallization from THF, leads to isolation of NdI3(TKF)(x) (1). Compound 1 reacts with one equiv of KC5Me5 to produce the mono-pentamethylcyclopentadienyl derivative (eta-C5Me5)NdI2(THF)(3) (2) in moderate yield. Treatment of 2 with an excess of pyridine in toluene leads to displacement of the THF ligands and formation of the tris-pyridine adduct (eta-C5Me5)NdI2(py)(3) (3). Compound 3 reacts with one equiv of KC5H4SiMe3 to yield the mixed-ring complex (eta-C5Me5)(eta-C5H4SiMe3)NdI(py) (4). Single crystal X-ray diffraction studies have been performed on complexes 3 and 4. (eta-C5Me5)NdI2(py)(3) (3) adopts a pseudo-octahedral geometry in the solid state, with the cyclopentadienyl ligand occupying one coordination site, the three pyridine ligands in a mer-configuration, and the iodide ligands trans to one another. The Nd-I distance is 3.1603(5) Angstrom, while Nd-N bond lengths to the pyridine ligands are 2.631(4) and 2.678(6) Angstrom. The solid state structure of (eta-C5Me5)(eta-C5H4SiMe3)NdI(py) (4) features a typical bent metallocene Cp2MX2 geometry with Nd-I and Nd-N distances of 3.0664(4) and 2.555(4) Angstrom, respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.