Synthesis and characterization of 2-pyridylalkoxide complexes of titanium, zirconium and tantalum. Crystal structures of TiCp*Me2(OCMePy2) and TaCp*Cl3(OCPy3) (Cp*=η5-C5Me5, Py=C5H4N)

Abstract

The methyltitanium derivative TiCp*Me₃ (Cp* = η⁵-C₅Me₅) reacted with tris(2-pyridyl)methyl alcohol, HOCPy₃, to yield the alkoxide complex TiCp*Me₂(OCPy₃) 1. The reaction of TiCp*Me₃ with di-2-pyridyl ketone, Py₂CO, yielded, through an insertion process, the corresponding alkoxide derivative TiCp*Me₂(OCMePy₂) 2. In order to establish the co-ordination mode of the alkoxide ligand, X-ray diffraction studies were carried out on complex 2. Insertion of di-2-pyridyl ketone into a Ta–Me bond of TaCp*Me₄ gave the corresponding alkoxide compound TaCp*Me₃(OCMePy₂) (3). Metathesis reaction of titanium and zirconium complexes MCp*Cl₃ with the lithium alkoxide LiOCRPy₂ led to the corresponding derivatives MCp*Cl₂(OCRPy₂) [M = Ti, R = Me (4) or Py (5); M = Zr, R = Me (6) or Py (7)]. In an analogous way, tantalum derivatives TaCp*Cl₃(OCRPy₂) [R = Me (8) or Py (9)] can also be synthesized by reaction of TaCp*Cl₄ with the appropriate lithium alkoxide LiOCRPy₂. The crystal structure of complex 9 has been determined by X-ray diffraction.