Improved 29Si NMR detection of sterically protected fluorosilanes using the 29Si(19F)-INEPT technique

“…29 SiA C H T U N G T R E N N U N G { 19 F}-INEPT spectra were recorded on a GEMINI 300 spectrometer. [37] Mass spectrometry: Electrospray mass spectra were recorded on a Thermo LCQ-DUO ion trap mass spectrometer (Thermo, San Jose, CA, USA) equipped with a nano-ESI source using metal coated nano-ESI needles (Proxxeon, Odense, Denmark; outer diameter, 360 mm; inner diameter, 75 mm), employing a spray voltage of 1.5 kV and concentrations of 0.5-1.0 mg mL À1 in CHCl 3 . Normalized collision energies were incremented in 5 % steps between 5 and 30 %.…”

Section: Methodsmentioning

confidence: 99%

Exploring the Anion–Cation Interaction in m‐Terphenyltetrafluorosilicates by Using Multinuclear NMR Spectroscopy, X‐ray Diffraction, and ICR‐FT‐MS

Spirk

Belaj

Nieger

et al. 2009

Chemistry A European J

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The synthesis of a series of m-terphenyl-substituted tetrafluorosilicates with different cations (Na(+), K(+), Rb(+), Cs(+), Ag(+), Tl(+)) is described and the interactions between the anion and cation are investigated in the solid, solution, and gas states by using multinuclear NMR spectroscopy, X-ray diffraction, and ion cyclotron resonance Fourier-transform mass spectrometry (ICR-FT-MS). In solution, heteronuclear NMR spectroscopy parameters show only limited sensitivity to the nature of the cation, which furthermore can be affected by solvent effects. More pronounced effects are observed in the structural data obtained from X-ray diffraction studies, which are in good agreement with experimental gas-phase data from ESIMS. ESIMS also reveals the existence of dimeric species of the type [M(DmpSiF(4))(2)](-) (Dmp = 2,6-dimesitylphenyl), the stability of which was determined by normalized collision energy experiments.

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“…The shortening of the primary Si-F bond and the increase in the coordination number of the Si atom from 4 to 4+4 can be attributed to the high electronegativity difference of Si and F and the ionic character of the Si-F bond. The title compound m-terphenyltrifluorosilane 2,6-Mes 2 C 6 H 3 SiF 3 is a rare example of a simple aryltrifluorosilane that has been fully characterized by X-ray crystallography (Pietschnig et al, 2000) as well as solution and solid-state NMR spectroscopy (Helluy et al, 2003;Pietschnig, 2007). Both SiF 4 and 2,6-Mes 2 C 6 H 3 SiF 3 are Lewis acidic and react with excessive fluoride ions to give the fluorosilicate ions SiF 6 2-and 2,6-Mes 2 C 6 H 3 SiF 4 -, respectively (Pietschnig and Merz, 2001;Spirk et al, 2009).…”

mentioning

confidence: 99%