Oxo- und Thiotantal(V)-Verbindungen: Synthese von TaOX3 und TaSX3 (X = OR,SR)

Oxo- and Thiotantalum(V) Compounds: Synthesis of TaOX₃ and TaSX₃ (X = OR, SR) TaO(OR)₃ [R = ^tC₄H₉, Mes* ( 2 )], TaO(SR)₃ [R = ^tC₄H₉, p-Tolyl], TaS(OR)₃ [R = ^tC₄H₉, Mes* ( 6 )] and TaS(SR)₃ [R = ^tC₄H₉, p-Tolyl] have been prepared by reaction of TaOCl₃ and TaSCl₃ with LiOR or LiSR. The reaction of TaCl₅ with an excess of LiOMes* yields the chlorotantalum(V)compounds TaCl₃(OMes*)₂ and TaCl₂(OMes*)₃ ( 10 ). The synthesis of TaCl₂(ⁿC₄H₉)(OMes*)₂ ( 11 ), Ta(Sp-Tolyl)₅ and TaCl₂(OEt)₃ · C₅H₅N are also described. 2, 6, 10 and 11 decompose in benzolic solution or by heating under vacuum splitting off 2,4,6-tri-tert-butyl-phenol, n-butane respectively, and forming cyclometallated tantalum(V) complexes with the bidentate ligand OC₆H₂^tBu₂CMe₂CH₂. TaCl₂(OEt)₃ was investigated by X-ray diffraction analysis; the crystal structure has been found to be a binuclear tantalum complex with two bridging ethoxo ligands.