Synthesis and structure of isopropyldimethylsilyl-substituted octamethyltitanocene

Reactivity of SiMe2H Substituents in Permethylated Titanocene Complexes: Dehydrocoupling and Ethene Hydrosilylation

“…Compound 5 displayed a 1 H NMR spectrum consisting of two downfield shifted signals at 77.06 and 25.88 ppm and additional signals at 6.13, 5.73, and 5.14 ppm, which all showed thermally dependent paramagnetic shifts (see Supporting Information) similar to those found for titanocenes [Ti{η 5 -C 5 Me 4 (SiMe 3 )} 2 ], [Ti{η 5 -C 5 Me 4 (SiMe 2 i Pr)} 2 ], [Ti{η 5 -C 5 Me 4 (SiMe 2 t Bu)} 2 ], [Ti(η 5 -C 5 Me 5 ) 2 ], , [Ti{η 5 -C 5 Me 4 ( t Bu)} 2 ], and [Ti{η 5 -C 5 Me 4 ( i Pr)} 2 ] . The NMR spectra of 6 were obtained in a mixture with those of 7 (for additional NMR data see Supporting Information), which was initially a minor component only.…”

“…The ν (CC) valence vibration of the coordinated btmse occurred as three bands: 1643 (w), 1602 (m), 1568 (m). The appearance of these bands is similarly complex for [Ti{η 5 -C 5 Me 4 (SiMe 3 )} 2 (η 2 -btmse)] (1620 (sh), 1595 (m), 1560 (sh)), [Ti{η 5 -C 5 Me 4 (SiMe 2 i Pr)} 2 (η 2 -btmse)] (1634 (w), 1599 (s), 1562 (w)), and [Ti(η 5 -C 5 Me 5 ) 2 (η 2 -btmse)] (1598 (m), 1563 (w)) and other less methylated titanocene complexes . The reason for this complexity has not yet been elucidated.…”

“…The 1 H, 13 C, and 29 Si NMR spectra identified the presence of one paramagnetic product, one major diamagnetic product, and one minor diamagnetic product. The 1 H spectrum of the paramagnetic product can be assigned to [Ti{η 5 -C 5 Me 4 (SiMe 2 Et)} 2 ] ( 5 ) on the basis of comparison with the spectra of [Ti{η 5 -C 5 Me 4 (SiMe 3 )} 2 ], [Ti{η 5 -C 5 Me 4 (SiMe 2 i Pr)} 2 ], [Ti{η 5 -C 5 Me 4 (SiMe 2 t Bu)} 2 ], and [Ti(η 5 -C 5 Me 5 ) 2 ]. , The diamagnetic major product appeared to be the complex of [Ti{η 5 -C 5 Me 4 (SiMe 2 Et)} 2 (η 2 -C 2 H 4 )] ( 6 ) with π-coordinated ethene. The correct selection of resonances of 6 was corroborated by their disappearance after aging the sample for 1 week in darkness.…”

Molecular Main Group Metal Hydrides

“…A variety of heterobimetallic hydrido species bearing both magnesium and a transition metal center have been described. A majority arise serendipitously as a result of the use of a Group 2 metal as a reducing agent. ,− In contrast, and as part of their program to devise cooperative Main Group/transition metal-based systems for selective C–H and C–C bond activation, Crimmin and coworkers have reported a variety of mixed metal molecular species during the last five years . Oxidative addition of [( Dipp Nacnac)­Mg­(μ-H)] 2 ( 113 ) with a Rh­(III) intermediate, generated from the reductive elimination of triethylsilane from [Cp*Rh­(H) 2 (SiEt 3 ) 2 ], provided the heterobimetallic complex­[( Dipp Nacnac)­Mg­(H 2 )­Rh­(SiEt 3 )­(Cp*)] ( 216 ) along with a stoichiometric equivalent of triethylsilane (Scheme ).…”

Group 4 Transition Metal Sandwich Complexes: Still Fresh after Almost 60 Years

“…Mach and co-workers have since expanded on their initial finding and have prepared a family of (η 5 -C 5 Me 4 SiR 3 ) 2 Ti (SiR 3 = SiMe 2 CH 2 CH 2 Ph, SiMe 2 Ph, SiMePh 2 , SiMe 2 i Pr) titanium sandwich complexes. , Much like Lawless’ (η 5 -C 5 Me 4 SiMe 2 t Bu) 2 Ti derivative, each of these titanocenes has an S = 1 ground state and those that are structurally characterized exhibit parallel ring structures with the silyl groups oriented on opposite sides of the molecule. It is remarkable that isolation and structural characterization of titanium(II) sandwich compounds was elusive for 40 years and then two groups independently obtained two structures almost simultaneously!…”