Hafnium imido complexes containing silyl ligands

The hafnium imido dichloride (2,6-i-Pr2C6H3)NHf(THF)2Cl2 (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 monosilyl complex (2,6-i-Pr2C6H3)NHf(4-t-BuC5H4N)2Cl[Si(SiMe3)3] (4) was synthesized in a similar manner from (2,6-i-Pr2C6H3)NHf(4-t-BuC5H4N)2Cl2 (3) and one equivalent of (Me3Si)3SiK in good yield. The Cp*-containing hafnium imido complex {Cp*HfCl[μ-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)3SiH. Complex 5 was crystallographically characterized. Attempts to prepared derivatives of 5 with reactive σ-bonds resulted in the formation of Cp*-cyclometallated species.