Nuclear magnetic resonance spectroscopy of metal cyclopentadienyls X. Proton magnetic resonance spectra of, and dynamic behaviour in, bis(trimethylsilyl)cyclopentadiene

Highly fluorous zirconocene(IV) complexes and their catalytic applications in the polymerization of ethylene

“…Comparison with the values found in the literature for related compounds [37] suggests that the second most intense set of signals could correspond to two isomers (set b, Chart 1), whereas the set of signals of lowest intensity is due to four isomers (set c, Chart 1). The most characteristic resonances of set b, those due to the protons in the 5 position, appear at d 3.60 ppm, while the methylene protons in the same position for set c give rise to two multiplets at d 3.09 and 3.12 ppm.…”

Neutral and Cationic [Bis(η1‐amidosilyl)‐η5‐cyclopentadienyl]titanium and ‐zirconium Complexes: Synthesis, X‐ray Molecular Structures and DFT Calculations

“…In comparison with other previously reported disilyl-substituted compounds C 5 H 4 (SiR 3 ) 2 , [10] in which the 1,1-isomer (b; R ϭ Me, Cl) is by far the major component, the steric hindrance caused by the bulkier substituents (R ϭ NHtBu) means that the 1,3-isomer (a; two broad SiMe 2 singlets) is the major component in the isomeric mixture of 1, being more favourable than the 1,1-isomer (b; one broad SiMe 2 singlet), as shown in Scheme 2. The other two isomers (2,4-and 2,5-), with both silyl groups bound to sp 2 carbon atoms, were less abundant components.…”

“…The other two isomers (2,4-and 2,5-), with both silyl groups bound to sp 2 carbon atoms, were less abundant components. All of these isomers interconvert, probably through successive 1,2-shifts of the silyl groups, [10] and increasing temperatures increase the a/b ratio to 4:1 at 50°C, 8:1 at 70°C and more than 10:1 at temperatures higher than 80°C. The broad signals observed for 1a at 20°C appeared as four singlets when the 1 H NMR spectrum was recorded at Ϫ40°C.…”

“…They show one singlet ( 1 H) and two resonances ( 13 C) for the tBu groups and two signals ( 1 H and 13 C) for the non-equivalent methyl groups of the SiMe 2 moiety. Additionally, they show an A 2 B spin system for the ring protons and three signals for the ring carbon atoms, along with one resonance for the methyl (8, 9) and methylene (10,11) protons and carbon atoms of the NMe 2 and CH 2 Ph ligands, respectively. The ∆δ [15] values are larger than those observed for non-coordinated SiMe 2 NHtBu groups in monocyclopentadienyl (2, 3) and single silylamido (4Ϫ7) compounds, but lower than those observed for the metalcoordinated SiMe 2 -η 1 -NtBu groups in silylamido compounds (4Ϫ7).…”

Organosilanes

“…Those i n l o w oxidation states result through cleavage o f the tin-cyclopentadienyl bond (equations[234][235][236] 223. Those i n l o w oxidation states result through cleavage o f the tin-cyclopentadienyl bond (equations[234][235][236] 223.…”