Cyclopentadienyl-Amido Ligands with a Pendant “−NHR” Amino Functionality in Titanium Chemistry. Molecular Structure of [Ti{η5-C5H4SiMe2-η-N(CH2)2-η-NHCHMe2}Cl2]
摘要:
The reaction of the chlorodimethylsilyl-substituted cyclopentadienyl titanium compound [Ti(eta(5)-C5H4SiMe2Cl)Cl-3] (1) with 1 equiv of NH2(CH2)(2)NHR (R = H, CHMe2), in the presence of 2 equiv of NEt3, afforded the mononuclear complexes [Ti{eta(5)-C5H4SiMe2-eta-N(CH2)(2)-eta-NHR}Cl-2] (R = H, 2; CHMe2, 3) in high yield. While 2 is stable in solution, 3 slowly evolves into the strain-free complex [Ti{eta(5)-C5H4SiMe2NH(CH2)(2)-eta-NCHMe2}Cl-2] (4). 1 reacts with 0.5 equiv of ethylenediamine to yield a mixture of 2 and the dinuclear titanium complex [Ti{eta(5)-C5H4SiMe2-eta-N(CH2)-}Cl-2](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{eta(5)-C5H4SiMe2-N(CH2)(1.5)-}Cl-2](2) (6), whereas a mixture of 6 and the mononuclear species-[Ti{eta(5)-C5H4SiMe2-eta-N(CH2)(3)NH2}Cl-2] (7) was spectroscopically observed when 1 was reacted with 1 equiv of NH2(CH2)(3)NH2 in C6D6. A similar reaction of 1 with N-methylpropylenediamine regioselectively affords the unstrained mononuclear compound [Ti{eta(5)-C5H4SiMe2NH(CH2)(3)-eta-NMe}Cl-2] (8). Dinuclear derivatives [Ti{eta(5)-C5H4SiMe2-eta-N(CH2)(x)-}Cl-2](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.
Cyclopentadienyl-Silyl-Amido Niobium Complexes Prepared by a Transmetalation Reaction Using 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>NRR‘}Cl<sub>2</sub>
作者:M. Carmen Maestre、Vanessa Tabernero、Marta E. G. Mosquera、Gerardo Jiménez、Tomás Cuenca
DOI:10.1021/om0505312
日期:2005.11.1
Reaction of Tieta(5)-C5H4SiMe2-eta-N(CH2)(2)NRR'}Cl-2 with Nb(eta(5)-C5H4SiMe2Cl)Cl-4 affords the tethered heterodinuclear complexes TiCl2eta(5)-C5H4SiMe2-eta-N(CH2)(2)-K-NRR'}Nb(eta(5)-C5H4SiMe2-Cl)Cl-4, which are thermally unstable in solution and evolve to render an equimolar mixture of Ti(eta(5)-C5H4SiMe2Cl)Cl-3 and the corresponding cyclopentadienyl-amido niobium compounds, Nbeta(5)-C5H4SiMe2-eta-N(CH2)(2)NRR'}Cl-3. These compounds are straightforwardly obtained from the reaction of Nb(eta(5)-C5H4SiMe2Cl)Cl-4 with 1 equiv of the appropriate diamine, NH2(CH2),-NRR', in the presence of 2 equiv of NEt3, in high yield. In this reaction, the presence of the functional pendant chain plays a central role not only in determining the course of the reaction but also in stabilizing the final product, from both an electronic and a steric point of view. The molecular structure of Nbeta(5)-C5H4SiMe2-eta-N(CH2)(3)-eta-NH2]Cl-3 has been determined by X-ray diffraction methods.