(Diphenylphosphino)methyl complexes of titanium and zirconium: Synthesis and characterization. Molecular structure of CpCp*Ti(CH2PPh2)2 (Cp = C5H5; Cp* = C5Me5)

Article abstract of DOI:10.1021/om00038a041

The reaction of [C₅(CH₃)₅](C₅H₅)MCl ₂ (M = Ti, Zr) with 2 equiv of LiCH₂PPh₂·TMEDA offers a convenient method for the preparation of the corresponding dialkyl derivatives [C₅(CH₃)₅](C₅H ₅)M-(CH₂PPh₂)₂ where M = Ti and Zr in 95-100% yield. However, when this reaction is carried out with 1 equiv of LiCH₂PPh₂·TMEDA in the same conditions, the chloro alkyl complex of titanium [C₅-(CH₃)₅](C₅H ₅)TiCl(CH₂PPh₂) is formed, whereas a mixture of the starting material and the dialkyl derivative is obtained for zirconium. These new complexes have been characterized by ¹H, ¹³C, and ³¹P{¹H} NMR measurements and elemental analysis. The ¹H NMR spectra show a clear diastereotopic behavior for the methylene protons of the CH₂ groups. The molecular structure of [C₅(CH₃)₅](C₅H ₅)Ti(CH₂PPh₂)₂ as determined by X-ray diffraction methods is reported. The complex crystallizes in the space group P2₁/c (No. 14), a = 17.323 (2) A?, b = 12.549 (1) A?, c = 16.497 (2) A?, β = 103.71 (2)°, Z = 4. The geometry around the Ti atom is normal. A weak agostic interaction Ti?H(4) can be proposed to be present in the structure of the solid state of this compound.