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Synthesis, Reactivity, and Insights into the Lewis Acidity of Mononuclear Titanocene Imido Complexes Bearing Sterically Demanding Terphenyl Moieties
Organometallics ( IF 2.5 ) Pub Date : 2020-08-31 , DOI: 10.1021/acs.organomet.0c00452
Malte Fischer 1 , Marie Christin Wolff 2 , Estefanía del Horno 3 , Marc Schmidtmann 2 , Rüdiger Beckhaus 2
Affiliation  

The titanocene imido complex 2 with a m-terphenyl moiety is synthesized by reacting Cp2Ti(η2-Me3SiC2SiMe3) (1) with m-terphenyl azide. Subsequent reactivity studies with tetrahydrofuran, pyridine, and nitriles verify that these substrates act as two-electron donors, thus binding end-on to the titanium center to give the donor-stabilized titanocene imides 3a,b and 4ac. Given the potential of the titanium center to act as an electron acceptor, 2 was reacted with phosphine oxides (OPEt3/OPPh3) according to the Gutmann–Beckett method to get information about the Lewis acidity of 2 and to yield 5a,b. Complex 5a is one of the rare examples of structurally characterized titanium complexes with an η1-bound cyclopentadienyl ligand. Further insights into the Lewis acidity of 2 were obtained from the nitrile adducts 4ac through IR spectroscopy and NMR spectroscopy (δ(19F) and 1JC,F employing 4-fluorobenzontrile). In reactions of 2 with terminal alkynes, the respective titanium amido acetylides 6a,b were obtained, whereas reactions with internal alkynes demonstrate that 2 is not very prone to undergoing [2 + 2] cycloaddition reactions.

中文翻译:

合成,反应性和对具有立体要求的三联苯部分的单核二茂钛亚氨基配合物的路易斯酸的见解。

作为二茂钛络合物酰亚胺2三联苯的部分是通过使合成的Cp 2的Ti(η 2 -Me 3的SiC 2森达3)(1)用-三联苯叠氮化物。随后用四氢呋喃,吡啶和腈进行的反应性研究证明,这些底物起着两个电子供体的作用,因此末端与钛中心结合,得到了供体稳定的二茂钛酰亚胺3ab4a - c。鉴于钛中心具有充当电子受体的潜力,2根据Gutmann–Beckett方法,将其与氧化膦(OPEt 3 / OPPh 3)反应,以获得有关路易斯酸2的信息,并产生5ab。复杂的图5a是在结构上,其特征在于钛络合物的与η罕见例子之一1结合的环戊二烯基配位体。通过IR光谱和NMR光谱(δ(19 F)和1 J C,F使用4-氟苯甲腈)从腈加合物4ac中获得了对2的路易斯酸度的进一步了解。在2的反应中在末端炔烃的情况下,获得了相应的钛酰胺基乙炔化物钛6ab,而与内部炔烃的反应表明2不太容易发生[2 + 2]环加成反应。
更新日期:2020-09-14
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