2-[(4-Chlorophenyl)sulfanyl]-2-methoxy-1-phenylethan-1-one: crystal structure and Hirshfeld surface analysis

The title compound, C15H13ClO2S, comprises (4-chlorophenyl)sulfanyl, benzaldehyde and methoxy residues linked at a chiral methine-C atom (the crystal is racemic). A twist in the methine-C—C(carbonyl) bond [O—C—C—O torsion angle = 19.3 (7)⁰] leads to a dihedral angle of 22.2 (5)⁰ between the benzaldehyde and methine+methoxy residues. The chlorobenzene ring is folded to lie over the O atoms, with the dihedral angle between the benzene rings being 42.9 (2)⁰. In the crystal, the carbonyl-O atom accepts two C—H...O interactions with methyl- and methine-C—H atoms being the donors. The result is an helical supramolecular chain aligned along the c axis; chains pack with no directional interactions between them. An analysis of the Hirshfeld surface points to the important contributions of weak H...H and C...C contacts to the molecular packing

2-[(4-Bromophenyl)sulfanyl]-2-methoxy-1-phenylethan-1-one: crystal structure, Hirshfeld surface analysis and computational chemistry

The title compound, C15H13BrO2S, comprises three different substituents bound to a central (and chiral) methine-C atom, i.e. (4-bromophenyl)sulfanyl, benzaldehyde and methoxy residues: crystal symmetry generates a racemic mixture. A twist in the molecule is evident about the methine-C—C(carbonyl) bond as evidenced by the O—C—C—O torsion angle of -20.8 (7)⁰. The dihedral angle between the bromobenzene and phenyl rings is 43.2 (2)⁰, with the former disposed to lie over the oxygen atoms. The most prominent feature of the packing is the formation of helical supramolecular chains as a result of methyland methine-C—H...O(carbonyl) interactions. The chains assemble into a three-dimensional architecture without directional interactions between them. The nature of the weak points of contacts has been probed by a combination of Hirshfeld surface analysis, non-covalent interaction plots and interaction energy calculations. These point to the importance of weaker H...H and C—H...C interactions in the consolidation of the structure

Conformational analysis of some 4'-substituted 2-(phenylselanyl)- 2-(methoxy)- acetophenones

A conformational study of some 4’-substituited 2-(phenylselanyl)-2-(methoxy)-acetophenones (OMe 1, H 2, and Cl 3) was performed using IR carbonyl stretching band analysis supported by NBO and PCM calculations at the B3LYP/6-31+G (d,p) level for 1-3 and using X-ray diffraction for 1 and 2. The computational results indicated the existence of three stable conformers for the series (c2, c3, and c1 in order of decreasing stability), whose relative abundance changes with solvent permittivity. The experimental trend observed for the components of the triplet carbonyl band in all solvents matches well with computational results and thus allows for their assignment to distinct conformers. The relative population of the c1 conformer increases in more polar solvents, becoming the most stable conformer in the highest permittivity solvent, acetonitrile, as indicated by IR spectra and PCM calculations. These findings are related to the quasi parallel geometry assumed by the Cδ+=Oδ- and Cδ+-Oδ- dipoles, which favour stronger solvation. NBO analysis shows that the sum of the energies (ΣE) of the relevant orbital interactions stabilises the c3 conformer of 1-3 slightly, likely due to the minor contribution of the LPO5→σ*C3-Se10 interaction. However, only the c1 conformer is significantly destabilized by the Oδ-(1)CO…Oδ-(5)OMe short contact electrostatic repulsion, which is also responsible for its highest νCO frequency. In addition, the LPO5→ σ*C2-C3 orbital interaction accounts for the lowest νCO frequency of c3 conformer. X-ray single crystal analysis of compounds 1 and 2 indicates that in the solid state they assume the least stable c1 conformation found in the gas phase. Molecules of these compounds are stabilised in the crystal through a series of C-H…O and C-H…π intermolecular interactions

Crystal structure of 2-methoxy-2-[(4-methylphenyl)sulfanyl]-1-phenylethan-1-one

In the title β-thiocarbonyl compound, C16H16O2S, the carbonyl and methoxy O atoms are approximately coplanar [O—C—C—O torsion angle = −18.2 (5)°] and syn to each other, and the tolyl ring is orientated to lie over them. The dihedral angle between the planes of the two rings is 44.03 (16)°. In the crystal, supramolecular chains are formed along the c axis mediated by C—H...O interactions involving methine and methyl H atoms as donors, with the carbonyl O atom accepting both bonds; these pack with no specific intermolecular interactions between them

Spectroscopic and theoretical studies of some 2‑(methoxy)‑2‑[(4‑substituted)‑phenylsulfanyl]‑(4′‑substituted) acetophenones

The conformational analysis of some 2‑(methoxy)‑2‑[(4‑substituted)‑phenylsulfanyl]‑(4′‑substituted) acetophenones was performed through infrared (IR) spectroscopic analysis of the carbonyl stretching band (νCO), supported by B3LYP/6-31+G(d,p) calculations and X-ray diffraction. Five (1–5) of the seven studied compounds (1–7) presented Fermi resonance (FR) on the νCO fundamental transition band. Deuteration of these compounds (1a–5a) precluded the occurrence of FR, revealing a νCO doublet for all compounds in all solvents used. The computational results indicated the existence of three conformers (c1, c2 and c3) for the whole series whose relative abundances varied with solvent permittivity. The higher νCO frequency c1 conformer was assigned to the higher frequency component of the carbonyl doublet, while both c2 and c3 were assigned to the lower frequency one. Anharmonic vibrational frequencies and Potential Energy Distribution (PED) calculations of compound 3 indicated that the combination band (cb) between the methyne δCH and one skeletal mode couples with the νCO mode giving rise to the FR on the c2 conformer in vacuum and on the c1 one in non-polar solvents. The experimental data indicated a progressive increase in c1 conformer stability with the increase of the solvent dielectric constant, which is in good agreement with the polarizable continuum model (PCM) calculations. The higher νCO frequency and the stronger solvation of the c1 conformer is a consequence of the repulsive field effect (RFE) originated by the alignment and closeness of the Cδ+[dbnd]Oδ− and Cδ+–Oδ− dipoles. Finally, the balance between orbital and electrostatic interactions dictates the conformational preferences. X-ray single crystal analysis for compound 6 revealed the c1 geometry in the solid state and its stabilization by C–H…O hydrogen bonds