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Decamethyltitanocene hydride intermediates in the hydrogenation of the corresponding titanocene-(eta(2)-ethene) or (eta(2)-alkyne) complexes and the effects of bulkier auxiliary ligands
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SYSNO ASEP 0482774 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Decamethyltitanocene hydride intermediates in the hydrogenation of the corresponding titanocene-(eta(2)-ethene) or (eta(2)-alkyne) complexes and the effects of bulkier auxiliary ligands Author(s) Pinkas, Jiří (UFCH-W) RID, ORCID
Gyepes, R. (SK)
Císařová, I. (CZ)
Kubišta, Jiří (UFCH-W) RID, ORCID
Horáček, Michal (UFCH-W) RID, ORCID
Mach, Karel (UFCH-W) ORCID, RIDSource Title Dalton Transactions. - : Royal Society of Chemistry - ISSN 1477-9226
Roč. 46, č. 25 (2017), s. 8229-8244Number of pages 6 s. Language eng - English Country GB - United Kingdom Keywords spin-resonance spectra ; cyclopentadienyl ligands ; dinitrogen complexes ; sandwich complexes ; carbon-monoxide Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry R&D Projects GAP207/12/2368 GA ČR - Czech Science Foundation (CSF) GP203/09/P276 GA ČR - Czech Science Foundation (CSF) Institutional support UFCH-W - RVO:61388955 UT WOS 000404467500028 EID SCOPUS 85021739743 DOI 10.1039/c7dt01545c Annotation H-1 NMR studies of reactions of titanocene [Cp*Ti-2] (Cp*=eta(5)-C5Me5) and its derivatives [Cp*(eta(5):eta(1)-C5Me4CH2)TiMe] and [Cp*Ti-2(eta(2)-CH2=CH2)] with excess dihydrogen at room temperature and pressures lower than 1 bar revealed the formation of dihydride [Cp*2TiH2] (1) and the concurrent liberation of either methane or ethane, depending on the organometallic reactant. The subsequent slow decay of 1 yielding [Cp*2TiH] (2) was mediated by titanocene formed in situ and controlled by hydrogen pressure. The crystalline products obtained by evaporating a hexane solution of fresh [Cp*Ti-2] in the presence of hydrogen contained crystals having either two independent molecules of 1 in the asymmetric part of the unit cell or cocrystals consisting of 1 and [Cp*Ti-2] in a 2 : 1 ratio. Hydrogenation of alkyne complexes [Cp*Ti-2(eta(2)-(RC)-C-1 CR2)] (R-1 = R-2 = Me or Et) performed at room temperature afforded alkanes (RCH2CH2R2)-C-1, and after removing hydrogen, 2 was formed in quantitative yields. For alkyne complexes containing bulkier substituent(s) R-1 = Me or Ph, R-2 = SiMe3, and R-1 = R-2 = Ph or SiMe3, successful hydrogenation required the application of increased temperatures (70-80 degrees C) and prolonged reaction times, in particular for bis(trimethylsilyl)acetylene. Under these conditions, no transient 1 was detected during the formation of 2. The bulkier auxiliary ligands eta(5)-(CMe4Bu)-Me-5-Bu-t and eta(5)-C5Me4SiMe3 did not hinder the addition of dihydrogen to the corresponding titanocenes [(eta(5)-(C5Me4Bu)-Bu-t)(2)Ti] and [(eta(5)-C5Me4SiMe3) Ti-2] yielding [(eta(5)-(C5Me4Bu)-Bu-t)(2)TiH2] (3) and [(eta(5)-C5Me4SiMe3)(2)TiH2] (4), respectively. In contrast to 1, the dihydride 4 did not decay with the formation of titanocene monohydride, but dissociated to titanocene upon dihydrogen removal... Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2018
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