Methyl 2,2-dimeth-oxy-5,5-bis-(methyl-sulfan-yl)-3-oxopent-4-enedithio-ate.

In the title mol-ecule, C(10)H(16)O(3)S(4), a short intra-molecular S⋯O(=C) distance [2.726 (2) Å] indicates the presence of a nonbonding attractive inter-action. In the crystal, mol-ecules are linked into centrosymmetric dimers via weak inter-molecular C-H⋯O and S⋯S [3.405 (3) Å] inter-actions. These dimers are linked by further weak C-H⋯O inter-actions into columns along the a axis.

2-Methyl-sulfan-yl-1H-perimidin-3-ium iodide.

In the structure of the title salt C(12)H(11)N(2)S(+)·I(-), the methyl-sulfanyl group of the cation is nearly coplanar with the perimidine rings, as indicated by the C-S-C-N torsion angles of 2.9 (5) and -177.2 (3)°, respectively. The (S)C-N bond lengths in the heterocyclic ring are approximately equal [1.325 (5) and 1.326 (6) Å] suggesting a degree of delocalization. In the crystal, cations and anions are linked via two discrete N-H⋯I hydrogen bonds, forming chains along the b axis.

2-(1,3-Benzoxazol-2-yl)-1-phenyl-ethenyl benzoate.

In the title mol-ecule, C(22)H(15)NO(3), the configuration about the ethyl-enic double bond is Z configuration and it is approximately coplanar with the adjacent phenyl ring and benzoxazole ring system as indicated by the C(H)=C(O)-C(phen-yl)-C(phen-yl) and O(benzoxazole)-C-C(H)=C(O) torsion angles of 179.88 (15) and 5.7 (2)°, respectively. The dihedral angle between the essentially planar (r.m.s. deviation = 0.080 Å) 2-(1,3-benzoxazol-2-yl)-1-phenyl-ethenyl group and the benzoate phenyl ring is 61.51 (6)°. A short intra-molecular O⋯O non-bonded inter-action of 2.651 (2) Šis present.

Hartree-Fock, Møller-Plesset calculations and dynamic NMR study of 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one.

The experimental (1)H, (13)C NMR spectra of 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one were recorded in CDCl(3) at temperature range 213-323 K. The variable temperature spectra revealed a dynamic NMR effect which is attributed to restricted rotation around the C=C double bond. Fast exchange processes of deuterium atoms between CDCl(3) and 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one or fast exchange of proton between nitrogen and oxygen atoms of carbonyl group is also revealed by broadening of N-H (singlet) proton NMR signals. Proton and carbon theoretical chemical shifts of the title molecule were calculated by using RHF and MP2-GIAO levels and different basis sets in gas phase at 298 K. The calculated proton chemical shifts show that the experimental values have no agreement with theoretical values, but for carbon chemical shifts a good agreement achieved by using RHF with 6-31G basis set and MP2/3-21G, 6-31G basis sets. Discrepancies are attributed to either the limitations of calculating program, because the change of the structure while rotation are not considered. The results showed that to select of basis set has more important rule, because RHF-GIAO level calculation with 6-31G basis set in gas phase can excellently reproduce the (13)C NMR spectrum. Moreover, MP2/3-21G, 6-31G calculation has not significant influence on (13)C NMR chemical shifts with respect to RHF-6-31G.