Mixed Chloro(dialkylamido) Complexes of Zirconium and Hafnium

Abstract

Chloro(dialkylamido) complexes of the type (R2N)2MCl2(THF)2 (R = Me, Et; M = Zr and R = Me; M = Hf) were synthesized in a conproportionation reaction by adding an equimolar amount of the corresponding M(NR2)4 to an ether slurry of MCl4 in the presence of THF. X‐ray crystal structure determinations of (Et2N)2ZrCl2(THF)2 (1 a) and (Me2N)2ZrCl2 · (THF)2 (1 b) reveal a distorted octahedral coordination geometry where the sterically demanding dialkylamide ligands force the chloride and the THF ligands out of their ideal position. Dynamic NMR investigations indicate an equilibrium of complexes with coordinated THF at low temperature in accordance with the structure determined by X‐ray crystallography and of chloro‐amido complexes that do not bind THF (at higher temperature).

Dichlorobis(dibenzylamino)bis(tetrahydrofuran)zirconium(IV) toluene hemisolvate

“…It is obvious from these angles, and the others given in Table 1, that the distortion from an octahedral geometry is steric in nature, with the angles involving the bulky amide ligands widening and the angles between the smaller ligands being compressed to compensate. These much greater distortions from octahedral geometry than found in (II) were explained by Brenner et al (1995) as being due to the increased steric bulk of ethyl over methyl. The ClÐ ZrÐCl, NÐZrÐN and OÐZrÐO angles in (II) are 163.14 (3), 98.37 (12) and 81.45 (8) , respectively.…”

“…We have recently been interested in the ability of zirconium amides to catalyse ethylene polymerization (Armstrong et al, 2000), and as part of this study, we have prepared and structurally characterized the complex [{(PhCH 2 ) 2 N} 2 ZrCl 2 (thf) 2 ], (I) (thf is the tetrahydrofuran ligand), as a toluene hemisolvate. A search of the Cambridge Structural Database (Allen & Kennard, 1993) revealed only two complexes closely related to (I), namely [(Me 2 N) 2 -ZrCl 2 (thf) 2 ], (II), and [(Et 2 N) 2 ZrCl 2 (thf) 2 ], (III) (Brenner et al, 1995). Both of these complexes were formed by the ligand redistribution reaction of ZrCl 4 with equimolar amounts of the appropriate tetraamide, Zr(NR 2 ) 4 .…”

Reactions of Functional Groups at the Periphery of Group 4 Metallocene Frameworks: Selective Formation of a Cp-Bonded Azaboretidine Derivative by a Hydroboration Route

“…[20] -7-Aza-hydroxybenzotriazole (HOAt), [9b] 6-amino-6-methylfulvene, [8] ZrCl 4 (thf) 2 , [21] ZrCl 2 (NEt 2 ) 2 (thf) 2 , [14] and HB(C 6 F 5 ) 2 [7] were prepared according to literature procedures.…”

Synthesis, characterisation, and dehydrocoupling ability of zirconium complexes bearing hindered bis(amido)silyl ligands

“…21 In a subsequent step, we combined this zirco-Scheme 3 Reaction of 2 with two and three equivalents of MeLi to form the methylated zirconium complexes 8 and 9, respectively. Fortuitously, Kempe and co-workers described the conproportionation of ZrCl 4 and Zr(NMe 2 ) 4 in a diethyl ether/ THF solvent mixture to afford the requisite precursor Cl 2 Zr-(NMe 2 ) 2 ·2THF.…”