Synthesis and characterisation of novel zirconium(iv) derivatives containing the bis-amido ligand SiMe2(NRR′)2

Abstract

The silicon compounds SiMe₂(NRR′)₂ [NRR′ = NMe₂ (1), NEt₂ (2), NC₄H₈ (3), NHEt (4), NHⁱPr (5), NH^tBu (6), NMeBu (7)] have been synthesised via aminolysis of the dichloro species SiMe₂Cl₂ and their ligating ability has been investigated towards zirconium(IV). The dimer zirconium compound {Zr[(NⁱPr)₂SiMe₂]₂}₂ (8) has been synthesised by reacting ZrCl₄ with the lithium salt Li₂[(NⁱPr)₂SiMe₂] and its molecular structure has been determined in the solid state by X-ray diffraction analysis. The reaction of ZrCl₄ with SiMe₂(NRR′)₂ yields the Lewis adducts ZrCl₄[(NRR′)₂SiMe₂] [NRR′ = NMe₂ (10), NC₄H₈ (11), NHEt (12), NHⁱPr (13), NH^tBu (14), NMeBu (15)]. On the other hand, the mixed amido derivative Zr(NMe₂)₃(NHMe)[(N^tBu)SiMe₂(NH^tBu)] (9) has been obtained from the reaction of Zr(NMe₂)₄ with SiMe₂(NH^tBu)₂. The solution molecular structure and dynamics of the zirconium derivatives have been elucidated by 1D and 2D multinuclear NMR spectroscopy.