Zirconium bisamidinate complexes with sterically demanding ligands: structure, solution dynamics, and reactivity

Edwin Otten, Peter Dijkstra, Cindy Visser, Auke Meetsma, Bart Hessen

OnderzoeksoutputAcademicpeer review

29 Citaten (Scopus)


Bisamidinate zirconium dichloride and dimethyl complexes with the sterically demanding amidinate ligands [PhC(NAr)(2))](-) (A) and [PhC(NAr)(NAr')](-) (B) (Ar = 2,6-(Pr2C6H3)-Pr-i; Ar' = 2,6-Me2C6H3) were prepared. The steric demand of ligand A induces the unusual trans geometry in trans-(A)(2)ZrCl2, whereas (A)(2)ZrMe2 and (B)(2)ZrX2 (X = Cl, Me) adopt the more usual cis-X-2 geometry. The dynamic behavior of these complexes in solution was studied by 1D and 2D H-1 NMR spectroscopy. Reaction of (A)(2)ZrMe2 with H-2 leads, after stepwise hydrogenolysis of the Zr-Me bonds, to cyclometalation of the two amidinate ligands. The same product was obtained by thermolysis of the dimethyl complex. The square pyramidal five-coordinate 10 valence electron cationic monomethyl species [(A)(2)ZrMe](+) was generated and structurally characterized. Remarkably, the compound is unreactive toward ethylene, H-2, and CO. The sterically slightly less encumbered species [(B)(2)ZrMe](+) does polymerize ethylene, albeit with modest activity.

Originele taal-2English
Pagina's (van-tot)4374-4386
Aantal pagina's13
Nummer van het tijdschrift18
StatusPublished - 29-aug.-2005

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