Substituent effects in reduction-induced synthesis of ansa-titanocenes

0457558 - ÚFCH JH 2017 RIV NL eng J - Journal Article
Pinkas, Jiří - Císařová, I. - Gyepes, R. - Kubišta, Jiří - Mach, Karel - Horáček, Michal
Substituent effects in reduction-induced synthesis of ansa-titanocenes.
Transition Metal Chemistry. Roč. 41, č. 2 (2016), s. 143-152. ISSN 0340-4285. E-ISSN 1572-901X
R&D Projects: GA ČR(CZ) GAP207/12/2368
Institutional support: RVO:61388955
Keywords : synthesis * ansa-titanocenes
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 1.358, year: 2016

Bis{(diphenylvinylsilyl)tetramethylcyclopentadienyl}/ntitanium dichloride [TiCl2{g5-C5Me4(SiPh2CH=/nCH2)}2] (1) is reduced with a half molar equivalent of/nmagnesium to the monochloride ([TiCl{g5-C5Me4(SiPh2-/nCH=CH2)}2] (2), whereas one molar equivalent of magnesium/naffords the titanocene [Ti{g5-C5Me4(SiPh2CH=/nCH2)}{g5:g2-C5Me4(SiPh2CH=CH2)}] (3) stabilized by/ng2-coordination of one of the two vinyl groups to titanium(/nII). In the presence of excess magnesium, the vinyl/nmoieties of 3 undergo intramolecular coupling to afford the/nansa-titanocene [Ti(g5:g5:g2-C5Me4SiPh2CH=CHCH2CH2-/nSiPh2C5Me4)] (4) possessing the g2-coordinated double/nbond in lateral position of its ansa-chain. The symmetrical/nansa-titanocene [Ti(g5:g5:g2-C5Me4SiPh2CH2CH=CHCH2-/nSiPh2C5Me4)] (5) was not obtained although its DFT-calculated/nenergy is only slightly higher than that of 4. It is/nconsidered that transient 5 gives rise to non-identified tarlike/nby-products which inherently accompany the formation/nof 4.
Permanent Link: http://hdl.handle.net/11104/0258007