Infrared and Raman Spectra, conformations, ab initio calculations and spectral assignments of 1,3‐disilabutane (SiH₃CH₂SiH₂CH₃)

Abstract

Raman spectra of 1,3-disilabutane (SiH 3 CH 2 SiH 2 CH 3 ) as a liquid were recorded at 293 K and as a solid at 78 K. In the Raman cryostat at 78 K an amorphous phase was first formed, giving a spectrum similar to that of the liquid. After annealing to 120 K, the sample crystallized and large changes occurred in the spectra since more than 20 bands present in the amorphous solid phase vanished. These spectral changes made it possible to assign Raman bands to the anti or gauche conformers with confidence. Additional Raman spectra were recorded of the liquid at 14 temperatures between 293 and 137 K. Some Raman bands changed their peak heights with temperature but were countered by changes in linewidths, and from three band pairs assigned to the anti and gauche conformers, the conformational enthalpy difference 1 conf H.gauche-anti/ was found to be 0 ± 0.3 kJ mol −1 in the liquid. Infrared spectra were obtained in the vapor and in the liquid phases at ambient temperature and in the solid phases at 78 K in the range 4000-400 cm −1 . The sample crystallized immediately when deposited on the CsI window at 78 K, and many bands present in the vapor and liquid disappeared. Additional infrared spectra in argon matrixes at 5 K were recorded before and after annealing to temperatures 20-34 K. Quantum chemical calculations were carried out at the HF, MP2 and B3LYP levels with a variety of basis sets. The HF and DFT calculations suggested the anti conformer as the more stable one by ca 1 kJ mol −1 , while the MP2 results favored gauche by up to 0.4 kJ mol −1 . The Complete Basis Set method CBS-QB3 gave an energy difference of 0.1 kJ mol −1 , with anti as the more stable one. Scaled force fields from B3LYP/cc-pVQZ calculations gave vibrational wavenumbers and band intensities for the two conformers. Ł 965 m 960 m" 961 s, sh 968 m 958 m" 961 m,sh 956 m, sh, P? 959 vs 958 vs 17 A 0 954 m 948 s, sh 952 vs Ł 18 950 vs 954 m 951 m" 947 vvs 945 s, D 950 vs 947 vs 18 A 00

Conformations of Morpholine in Liquid and Adsorbed on Gold Nanoparticles Explored by Raman Spectroscopy and Theoretical Calculations

“…Theoretical calculations, especially the density functional theory (DFT) and Møller–Plesset second-order perturbation theory (MP2) calculations, usually have been used to optimize the structures and predict the energies and frequencies of molecules, , ions, clusters, − and molecule–metal complexes. , Recently, Raman spectroscopy combined with Quantum Chemical Calculations was applied to distinguish molecular conformers/rotamers, to explore the conformational equilibrium in the condensed state, − to assign the vibrational bands, and to interpret the adsorption orientation and interaction mechanism of the molecules absorbed on the noble metal surface. − …”

Facile Carboxylation of Sugarcane Bagasse and the Adsorption Mechanism for Cadmium Ions

“…48 The doublet at ca. 3000 cm −1 could be ascribed to −CH, 43 −CH 2, 44 −CH 3 , 44 and hydrogen atoms in aromatic rings. 49 Hydroxyl groups corresponding to the band at 3300 cm −1 were observed, in agreement with the FTIR result.…”

“…The Raman spectrum of NTB is shown in Figure . The band at 1415 cm –1 is assigned to −CH, −CH 2, and −COO – groups. The band at 1600 cm –1 should be ascribed to aromatic rings and −COO – groups (based on the FTIR result).…”

Microwave and Quantum Chemical Study of Allyldifluorosilane (H2C═CHCH2SiF2H)

“…Recently, there has been great interest in the syntheses and investigation of the spectroscopic, conformational, and structural properties of silicon-containing compounds. Recent examples include F 3 SiCH 2 CH 2 SiF 3 , cyclopropylmethylsilane, , ClCH 2 SiH 3 , Cl 2 CHSiH 3 , ClCH 2 SiF 3 , Cl 2 CHSiF 3 , diethylsilane, diethyldifluorosilane, vinyl silyl fluoride, H 3 SiCH 2 SiH 2 CH 3 , disilabutane, silacyclopentane, and ethylmethylfluorosilane …”

“…Recently, there has been great interest in the syntheses and investigation of the spectroscopic, conformational, and structural properties of silicon-containing compounds. Recent examples include F 3 SiCH 2 CH 2 SiF 3 , 1 cyclopropylmethylsilane, 2,3 ClCH 2 -SiH 3 , 4 Cl 2 CHSiH 3 , 4 ClCH 2 SiF 3 , 4 Cl 2 CHSiF 3 , 4 diethylsilane, 5 diethyldifluorosilane, 5 vinyl silyl fluoride, 6 H 3 SiCH 2 SiH 2 CH 3 , 7 disilabutane, 8 silacyclopentane, 9 and ethylmethylfluorosilane. 10 In this work, we focus on the little-investigated conformational and structural properties of compounds possessing the difluorosilane (-SiF 2 H) group, with allyldifluorosilane (H 2 CdCHCH 2 SiF 2 H) as an example.…”