Conformational study of some 4'-substituted 2-(phenylselanyl)-2-(ethylsulfanyl)-acetophenones.

The conformational analysis of some 4'-substituted 2-(phenylselanyl)-2-(ethylsulfanyl)-acetophenones bearing the substituents NO2 (1), Br (2), H (3), Me (4) and OMe (5) was performed by ν(CO) IR analysis, B3LYP/6-31+G(d,p) and single point polarisable continuum model (PCM) calculations, along with NBO analysis for 1, 3 and 5. Calculations for 1-5 indicate the existence of three stable conformations, c1, c2 and c3, whose stability depends on the balance between electrostatic and orbital interactions that are strictly related to the geometrical arrangement. The comparison between the experimental IR spectra in solution and the computed data in gas phase for 1-5 allows the c1 conformer to be assigned to the less intense component at higher frequency of the carbonyl doublet and both the c2 and c3 ones to the more intense lower frequency component.

Spectroscopic and theoretical studies of some 3-(4'-substituted phenylsulfanyl)-1-methyl-2-piperidones.

The analysis of the IR carbonyl bands of some 3-(4'-substituted phenylsulfanyl)-1-methyl-2-piperidones 1-6 bearing substituents: NO₂ (compound 1), Br (compound 2), Cl (compound 3), H (compound 4) Me (compound 5) and OMe (compound 6) supported by B3LYP/6-31+G(d,p) and PCM calculations along with NBO analysis (for compound 4) and X-ray diffraction (for 2) indicated the existence of two stable conformations, i.e., axial (ax) and equatorial (eq), the former corresponding to the most stable and the least polar one in the gas phase calculations.

3,3-Bis(4-bromo-phenyl-sulfan-yl)-1-methyl-piperidin-2-one.

In the title compound, C18H17Br2NOS2, the conformation of the piperidin-2-one ring is based on a half-chair with the methyl-ene C atom diagonally opposite the N atom being 0.649 (3) Å above the plane of the remaining five atoms (r.m.

3,3-Bis[(4-meth-oxy-phen-yl)sulfan-yl]-1-methyl-piperidin-2-one.

The piperidone ring in the title compound, C(20)H(23)NO(3)S(2), has a distorted half-chair conformation with the central methyl-ene atom of the propyl fragment lying 0.696 (1) Å out of the plane defined by the other five atoms (r.m.

1-Methyl-3,3-bis-(phenyl-sulfan-yl)piperidin-2-one.

The piperidone ring in the title compound, C(18)H(19)NOS(2), is in a distorted half-chair conformation, distorted towards a twisted boat, with the central methyl-ene C atom of the propyl backbone lying 0.606 (2) Å out of the plane defined by the other five atoms (r.m.

1-Methyl-3,3-bis-[(4-methyl-phen-yl)sulfan-yl]piperidin-2-one.

The piperidone ring in the title compound, C(20)H(23)NOS(2), has a half-chair distorted to a twisted-boat conformation [Q(T) = 0.5200 (17) Å]. One of the S-bound benzene rings is almost perpendicular to the least-squares plane through the piperidone ring, whereas the other is not [dihedral angles = 75.

1-(4-Bromo-phen-yl)-2-ethyl-sulfinyl-2-(phenyl-selan-yl)ethanone monohydrate.

In the title hydrate, C(16)H(15)BrO(2)SSe·H(2)O, the sulfinyl O atom lies on the opposite side of the mol-ecule to the Se and carbonyl O atoms. The benzene rings form a dihedral angle of 51.66 (17)° and are splayed with respect to each other.

3,3-Bis[(4-chloro-phen-yl)sulfan-yl]-1-methyl-piperidin-2-one.

The piperidone ring in the title compound, C(18)H(17)Cl(2)NOS(2), has a distorted half-chair conformation. The S-bound benzene rings are approximately perpendicular to and splayed out of the mean plane through the piperidone ring [dihedral angles = 71.86 (13) and 46.

2-(4-Methoxy-phenyl-sulfin-yl)cyclo-hexan-1-one.

The cyclo-hexa-none ring in the title compound, C(13)H(16)O(3)S, is in a distorted chair conformation. The intra-molecular S⋯O(carbon-yl) distance is 2.814 (2) Å.

1-Methyl-3-phenyl-sulfonyl-2-piperidone.

The piperidone ring in the title compound, C(12)H(15)NO(3)S, has a slightly distorted half-chair conformation with the methyl, carbonyl and phenyl-sulfonyl ring substituents occupying equatorial, equatorial and axial positions, respectively. Mol-ecules are connected into centrosymmetric dimers via C-H⋯O inter-actions and these associate into layers via C-H⋯O-S contacts. Further C-H⋯O inter-actions involving both the carbonyl and sulfonyl O atoms consolidate the crystal packing by providing connections between the layers.