In three 9-silyltriptycenes bearing chlorine, bromine and the methyl group in one of the peri positions, the silyl group suffers extreme hindrance of its reorientational motion. Owing to this, separate signals of the individual silyl group protons could be observed in NMR spectra at relatively high temperatures. For each compound, the measured values of J couplings of these protons to the 29Si ...

Accurate quantum chemical computations based on density functional theory (DFT) were performed on the series of 2-(4-(naphthalen-2-yl)-1,2,3-thiadiazol-5-ylthio)-N-acetamide (TTA) derivatives. The local reactivity of the acetamide derivatives as anti-HIV drugs were studied in terms of Fukui functions in the framework of DFT. The results based on the basis set superposition error (BSSE) correcti...

Binary nanoclusters are of great interest for understanding fundamental phenomena related to applied materials science. Herein, neutral silicon-rich silicon−boron clusters (SinBm, n = 3−8, m = 1−2) are characterized by means of resonant infrared-ultraviolet two-color ionization (IR-UV2CI) spectroscopy, mass spectrometry, and quantum chemical calculations. Global energy optimizations are employe...

Rotational coordinates about the C(3)–O(4) bonds of 2,4-dioxaheptane (DOH) and 2,4,6-trioxaheptane (TOH) are compared at correlated levels of electronic structure theory for gauche and trans orientations of the O(2)–C(3) bonds. TOH has overlapping anomeric effects, while DOH does not. The overlapping stereoelectronic effect shows its largest impact on the length of the O(2)–C(3) bond, which is ...

The first systematic study of the CrðH2OÞ n ðnZ1K4Þ series of clusters is herein presented at the level of the unrestricted DFT B3LYP level in conjunction with electron core potential basis sets. The present structures are relevant for laser-induced and laser-ablation syntheses of chromium compounds, and also for fundamental spectroscopy studies of metal-bearing species in the gas phase. Calcul...

1N-methyl-1S-methyl-2-nitroethylene (NMSM) is an important intermediate in the synthesis of anti-ulcer drug Ranitidine. NMSM is a push pull alkene equivalent to glycine possessing both electron-donating and withdrawing nitro group at both ends of olefinic bond. The solid phase FT-IR and FT-Raman spectra of NMSM have been recorded in the region 4000-400cm and 3500-100cm, respectively. The molecu...

The Acamprosate is a significant drug for alcohol abuse therapy, which may be an effective treatment for tinnitus, too. The Acamprosate has two possible tautomers, Keto and Enol tautomers. Each of the tautomers involves two important conformers. In this work, employing density functional theory (DFT) and handling the solvent effects with the PCM model, the structural parameters, energetic behav...

The hetero Diels–Alder (HDA) reactions of 1-diethoxyphosphonyl-1,3-butadiene with various nitroso dienophiles have been studied at the B3LYP/6-31G** level. Structural, energetic and electronic properties are discussed. These cycloadditions with nitroso dienophiles are characterized by a total proximal regioselectivity and an endo selectivity. The influence of the nitroso substitution on the act...

Making use of a combination of ab initio calculated geometries, orbital energies, and orbital spatial distributions as well as experimental information about bond lengths, bond energies, vibrational frequencies, and dipole moments, the nature of the terminal PO bond in phosphates such as (MeO)(3)PO was probed and compared to the case in MeO-P=O where P is trivalent and a PO pi bond is thus assu...

Using natural bond orbital theory, aromatic stabilisation energies (NBO-ASEs) were calculated for neutral and cationic monoheterocyclic three-membered rings C2H2X(R)n (X = group 14-17 elements of rows 3-5; R F, H or SiH3; n 0-2). Generally, there was a decrease in the (anti)aromatic nature molecule moving down as either stabilizing overlap (aromaticity) destabilising interactions (antiaromatici...