Hafnium imido complexes containing silyl ligands

The hafnium imido dichloride (2,6-i-Pr2C6H3)N=Hf(THF)(2)Cl-2 (1) reacts with two equivalents of Ph3SiLi(THF)(3) to yield the corresponding disilyl complex (2,6-i-Pr2C6H3)N=Hf(THF)(2)(SiPh3)(2) (2) in low yield. Compound 2 was crystallographically characterized. The hafnium monosityl complex (2,6-i-Pr2C6H3)N=Hf(4-t-BuC5H4N)(2)Cl[Si(SiMe3)(3)] (4) was synthesized in a similar manner from (2,6-i-Pr2C6H3)N=Hf(4-t-BuC5H4N)(2)Cl-2 (3) and one equivalent of (Me3Si)(3)SiK in good yield. The Cp*-containing hafnium imido complex {Cp*HfCl[mu-N(2,6-i-Pr2C6H3)]}(2) (5) was prepared by thermolysis of Cp*Hf[Si(SiMe3)(3)][NH(2,6-i-Pr2C6H3)]Cl via loss of (Me3Si)(3)SiH. Complex 5 was crystallographically characterized. Attempts to prepared derivatives of 5 with reactive sigma-bonds resulted in the formation of Cp*-cyclometallated species. (C) 2002 Elsevier Science B.V. All rights reserved.