Zirconium, hafnium and yttrium complexes containing two linked amido-tetramethylcyclopentadienyl ligands : Synthesis, reactivity and molecular structure of Hf(η5:η1-C5Me4SiMe 2NiPr)2

Article abstract of DOI:10.1016/S0277-5387(97)00493-2

Zirconium and hafnium complexes M(ηη¹-C₅Me₄SiMe ₂NR′)_xCl_(4-2x) (M = Zr, Hf; x = 1, 2; R′ = iPr, tBu) containing one or two linked amido-tetramethylcyclopentadienyl ligands C₅Me₄SiMe₂NR′ have been synthesized by the reaction of the dilithium derivative Li₂(C₅Me₄SiMe₂NR′) with MCl₄(THF)₂. The crystal structure of the hafnium complex Hf(η⁵: η¹-C₅Me₄SiMe₂NiPr)₂ has been determined by a single-crystal X-ray diffraction study and shows a C₂-symmetric helical metallocene, in which the amido ligands are bonded as π-donor ligands with Hf - N bond lengths of 2.115(2) A. The isoelectronic heterobimetallic yttrium complex Li[Y(η⁵:η¹-C₅Me₄SiMe ₂NCH₂CH₂OMe)₂] reacts with phenylacetylene to give the bis(phenylacetylide) derivative Li[Y{η⁵-C₅Me₄SiMe₂NH(CH ₂CH₂OMe)}₂(C=CPh)₂].