$\eta^2$-Pyrazolato zirconium complex, $(dmPz)_2$ $Zr(NEt$_2)_2$ (1a), has been prepared from the reaction of $Zr(NEt_2)_4$ with 3,5-dimethylpyrazole (dmPz). Treatment of \textbf{1a} with Me$_3$SiCl afforded the dichloride complex, $(dmPz)_2$ZrCl_2$ (1b).
The reaction of $(C_5Me_4H)SiMe_2Cl$ with 1-(1-pyrrolidinomethyl) pyrazole lithium salt in THF and subsequent acid-catalyzed hydrolysis of the pyrrolidinomethyl protecting group using column chromatography gave the pyrazolato ligand, 5-{(tetramethyl cyclopentadienyl)dimethylsilyl}pyrazole (2b). Reaction of 2b with $Ti(NMe_2)_4$ afforded trisamido complex, [5-{(tetramethyl cyclopentadienyl)dimethyl-silyl}pyrazole]tris (dimethylamino)titanium (2c).
$Li_2[(C_5Me_4)SiMe_2(N-t-Bu)]$ (3b) was treated with $TiCl_3(THF)_3$ to prepare Ti(III)-CGC complex, $[(C_5Me_4)SiMe_2(N-t-Bu)]TiCl)$. However, Ti(IV)-CGC complex, $[(C_5Me_4)SiMe_2(NNC_5H_{10})]TiCl_2$ (4c), was formed instead in low yield, which has been confirmed by mass spectroscopy and single crystal X-ray diffraction study.
A hydrazido ligand, $(C_5Me_4H)SiMe_2(N(H)NC_5H_{10})$ (4a), has been prepared from the reaction of $(C_5Me_4H)SiMe_2Cl$ with $LiNHNC_5H_{10}$ in diethyl ether. Reaction of the dilithiated ligand (4b) with $TiCl_3(THF)_3$ and subsequent oxidation with AgCl afforded the $\eta^2$-hydrazido complex, $[(\eta^5-C_5Me_4)SiMe_2(\eta^2-NNC_5H_{10})]TiCl_2$ (4c).