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Previously unknown 2-(1,2-dimethylindol-3-yl)-1-nitroethene was synthesized, and procedures for preparing 2-(1-methylbenzimidazol-2-yl)- and 2-(3-pyridyl)-1-nitroethens were improved. The structures of the products were determined by spectroscopic methods and from their dipole moments. According to single crystal X-ray diffraction data, the (E)-2-(1-methylbenzimidazol-2-yl)-1-nitroethene molecules are virtually planar and are packed in stacks in the crystal lattice, with appreciable stacking interaction.

A method was developed for preparing first representatives of phosphorylated nitrovinylindoles, bis(2-chloroethyl) 1-(indol-3-yl)- and bis(2-chloroethyl) 1-(1-alkylindol-3-yl)-2-nitroethenylphosphonates, and the structures of these compounds were studied. The spectroscopic data and results of dipole moment measurements show that the molecules have E configuration with s-cis arrangement of the multiple bond and phosphoryl group. X-ray studies have shown that the molecules of the first compound, having the E-s-cis form in the solid phase also, exist in the crystal in the form of enantiomeric pairs. They are involved in inter- molecular hydrogen bonds to form infinite chains.

Under conditions of the phase transfer catalysis, acylation of (thio)phosphorylacetonitriles by (het)aroyl chlorides affords the Z-enol forms of C-acylation products in high yields. Their configurations were studied by IR spectroscopy, dipole moment measurements, and ab initio quantum-chemical calculations [B3LYP/6-31G(d)]. The C=C double bond and the phosphoryl or thiophosphoryl group have an s-cis arrangement. The possibility of strong intramolecular hydrogen bonding in these conformers is the governing factor responsible for the three-dimensional structures of the compounds under investigation. Derivatives of nicotinic acid existing in the individual form as zwitterions are the only exceptions.

2-X-5,6-benzo-1,3,2-dioxaphosphinin-4-ones (X = N = C = O, Cl, NEt2), regardless of their aggregative state, prefer one and the same conformation (flattened sofa); the exocyclic substituent occupies either an axial (N = C = O, NEt2) or an equatorial (Cl) position.

A one-stage synthesis of 1-acyl-1-nitro-2-furyl(thienyl)ethenes was developed and structural assessment of the products was performed by means of 1H, IR, and UV spectroscopy and dipole moment measurements. The acetyl derivatives have Z configuration, and the benzoyl derivatives, E configuration. The UV and IR spectra, as well as the rather high dipole moments (μ ∼5-6 D) point to an essential contribution in the structures of dipolar forms.

A preparation method was developed for new representatives of halonitroenamines, 1-bromo-1-nitro-2-piperidino(cyclohexylamino)-2-phenylethenes. Both molecules possess E configuration and are of high polarity.