Crystal Structure of 1-(N-morpholiniomethyl)spirobi(4-methyl-3-oxo- 2,5-dioxa-1-silacyclopentan)ate Dihydrate, C11H19NO7Si • 2H2O

C11H23NO9Si, tetragonal, P41 (no. 76), a = 10.6634(4) Å, c = 14.8804(6) Å, V = 1692.0 Å3, Z = 4, Rgt(F) = 0.047, wRref(F2) = 0.118, T = 253 K

NMR and Quantum-Chemical Studies of Electrostatically Stabilized 1-(N,N-Substituted-aminiomethyl)spirobi [3-oxo(2,5-dioxa-1-silacyclopentan)]ates (ES-Silanates)

1-(N,N-substituted-aminiomethyl)spirobi[3-oxo(2,5-dioxa-1-silacyclopentan)]ates were investigated using NMR, X-ray, and quantum-chemical methods. The free activation parameters for the inversion of “ammonium-amine nitrogen” and the chirality change at the pentacoordinated silicon were determined by dynamic NMR spectroscopy. The latter proceeds via the dissociation of Si[BOND]O bonds. The results were confirmed by quantum-chemical calculations, the experimental observation of cross-peaks in 2D-EXSY NMR spectra, and the spirocycle exchange reactions. Transition pathways between the different diastereomers in solution were analyzed

NMR and Quantum-Chemical Studies of Electrostatically Stabilized 1-(N,N-Substituted-aminiomethyl)spirobi [3-oxo(2,5-dioxa-1-silacyclopentan)]ates (ES-Silanates)

1-(N,N-substituted-aminiomethyl)spirobi[3-oxo(2,5-dioxa-1-silacyclopentan)]ates were investigated using NMR, X-ray, and quantum-chemical methods. The free activation parameters for the inversion of “ammonium-amine nitrogen” and the chirality change at the pentacoordinated silicon were determined by dynamic NMR spectroscopy. The latter proceeds via the dissociation of Si[BOND]O bonds. The results were confirmed by quantum-chemical calculations, the experimental observation of cross-peaks in 2D-EXSY NMR spectra, and the spirocycle exchange reactions. Transition pathways between the different diastereomers in solution were analyzed

Separation of Selected Heptacoordinated Derivatives of Goshchava-Silanates for HPLC

Optimum conditions of separation and determination was studied of two newly synthesized heptacoordinated benzyl derivatives from the group of Goshchava-silanates: Homo{O,O′,O″,O‴-oxalic acid's Si-[N-benzylaminiomethyl]-Si,Si-dihydroxysilanate} and Homo{O,O′,O″,O‴-oxalic acid's Si-[N-benzylaminiomethyl]-Si,Si-diethoxysilanate}. In the carried out investigation, we considered three stationary phases (octadecyl, octyl, phenylbutyl) and two mobile phases (acetonitrile and dichloromethane) in various intensities of flow. The best selectivity and the highest separation factor (α = 9.08) was obtained using the mobile phase acetonitrile (100%) and the phenylbutyl column. To reliably optimize the process of separation and determination of the compounds on the phenylbutyl column, the validation of prepared methodology was done