The calculation of ²⁹Si NMR chemical shifts of tetracoordinated silicon compounds in the gas phase and in solution

Abstract

Aiming at the identification of an efficient computational protocol for the accurate NMR assessment of organosilanes in low-polarity organic solvents, (29)Si NMR chemical shifts of a selected set of such species relevant in organic synthesis have been calculated relative to tetramethylsilane (TMS, 1) using selected density functional and perturbation theory methods. Satisfactory results are obtained when using triple zeta quality basis sets such as IGLO-III. Solvent effects impact the calculated results through both, changes in substrate geometry as well as changes in the actual shieldings. Spin-orbit (SO) corrections are required for systems carrying more than one chlorine atom directly bonded to silicon. Best overall results are obtained using gas phase geometries optimized at MPW1K/6-31+G(d) level in combination with shielding calculations performed at MPW1K/IGLO-III level in the presence of the PCM continuum solvation model.

A Disilene Base Adduct with a Dative Si–Si Single Bond

“…Spectroscopic features and bonding were evaluated by density functional theory (DFT) computations . Spin‐orbit relativistic 29 Si NMR chemical shift calculations on 1 are in good agreement with the observed signatures and confirm the assignment from 2D 1 H– 29 Si NMR spectroscopy (cf. Supporting Information).…”

1,2:5,6-Di-O-Cyclohexylidene-d-Mannitol and Its Bis(Trimethylsilyl) Ether in the Dithiophosphorylation Reactions

“…The attachment of the trimethylsilyl group to the sulfur atom of 7 was also confirmed by the 29 Si‐{ 1 Н} NMR spectrum in benzene containing a sharp singlet at δ = 33.0. This resonance is consistent with the presence of tetracoordinate silicon atom in 7 .…”

Spontaneous vs. Base‐Induced Dehydrochlorination of Group 14 ortho‐Carboranylamidinates

“…The latter signal is very weak and was not observed in 2 and 7 – 9 . The chemical shift of the E atom is in the expected range for silanes ( 7 – 9 : δ Si = –17.0 to +8.4 ppm), stannanes, ( 2 – 5 : δ Sn = –311 to –105 ppm), and plumbanes ( 6 : δ Pb = –255 ppm), respectively.…”