Cyclopentadienyl-Amido Ligands with a Pendant “−NHR” Amino Functionality in Titanium Chemistry. Molecular Structure of [Ti{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>SiMe<sub>2</sub>-η-N(CH<sub>2</sub>)<sub>2</sub>-η-NHCHMe<sub>2</sub>}Cl<sub>2</sub>]
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The reaction of the chlorodimethylsilyl-substituted cyclopentadienyl titanium compound [Ti(η5-C5H4SiMe2Cl)Cl3] (1) with 1 equiv of NH2(CH2)2NHR (R = H, CHMe2), in the presence of 2 equiv of NEt3, afforded the mononuclear complexes [Ti{η5-C5H4SiMe2-η-N(CH2)2-η-NHR}Cl2] (R = H, 2; CHMe2, 3) in high yield. While 2 is stable in solution, 3 slowly evolves into the strain-free complex [Ti{η5-C5H4SiMe2NH(CH2)2-η-NCHMe2}Cl2] (4). 1 reacts with 0.5 equiv of ethylenediamine to yield a mixture of 2 and the dinuclear titanium complex [Ti{η5-C5H4SiMe2-η-N(CH2)−}Cl2]2 (5), which contains two tethered cyclopentadienyl-silyl-amido fragments. Compound 5 is also obtained from the reaction of 2 with 1. Treatment of 1 with 0.5 equiv of propylenediamine rendered the dinuclear compound [Ti{η5-C5H4SiMe2-η-N(CH2)1.5−}Cl2]2 (6), whereas a mixture of 6 and the mononuclear species [Ti{η5-C5H4SiMe2-η-N(CH2)3NH2}Cl2] (7) was spectroscopically observed when 1 was reacted with 1 equiv of NH2(CH2)3NH2 in C6D6. A similar reaction of 1 with N-methylpropylenediamine regioselectively affords the unstrained mononuclear compound [Ti{η5-C5H4SiMe2NH(CH2)3-η-NMe}Cl2] (8). Dinuclear derivatives [Ti{η5-C5H4SiMe2-η-N(CH2)x−}Cl2]2 (x = 2 (9); 2.5 (10)) were prepared by reacting complex 1 with butylenediamine and pentylenediamine, respectively. These compounds were characterized by elemental analysis and NMR spectroscopy. The crystal structure of 3 was determined by X-ray diffraction methods.
