Structure and reactivity of the condensation products of aromatic amines with aliphatic aldehydes

A number of previously undescribed propylidenearylamine dimers have been synthesized by the interaction of propionaldehyde with a series of para-substituted anilines(R=H, CH₃, OCH₃, F, Cl, Br, I) and with-naphthylamine. The structure of the bis-propylidenearylamines has been established by a study of their IR and UV spectra. It has been shown that all the bis-propylidenearylamines, except for bis(propylidene-p-fluoroaniline), have the structure of 2-ethyl-3-methyl-4-arylamino-1, 2, 3, 4-tetrahydroquinolines. The dipole moments of the bis(propylidene-p-R-anilines) have been determined. Comparison of the values obtained with the calculated values indicates that the most favorable molecular conformation of the bispropylidenearylamines is a tetrahydroquinoline half-chain with quasi-equatorial positions for the 4-NHAr and NH groups and an equatorial 3-CH₃ group. In contrast to the bis-ethylideneanilines, we did not succeed in finding other stable conformers for the bis-propylidene derivatives. It has been established that bis (propylidene-p-fluoroaniline) has the 1, 3-bis (p-fluorophenylamino)-2-ethyl-1-hexene structure.For communication VI, see [1].     

Structural equilibrium (S=0) ⇄ (S=1)and inversion of the configuration of the seven-membered saturated metal-containing ring in four-coordinate pyrazolealdiminate metal chelates of nickel(II) based on tetradentate ligands

¹H and¹³C NMR, x-ray structural analysis, and magnetic moment measurements have shown that in 5-thio(seleno)pyrazolealdiminate complexes of nickel(II) based on tetradentate ligands containing the fragment, with n=2, flattening of the chelate unit takes place in solution and in the solid state. A similar structure in which the diamine metal-containing ring has the twist-chair conformation is observed for the crystals of the complexes with n=4. For the complexes with n=4 in solution at a temperature below –50°C, rapid (on the NMR time scale) interconversion of the flattened (P) (S=0) and pseudotetrahedral (T) (S=1) structures is observed, not accompanied by inversion of the tetrahedral configuration of the metal atom. At temperatures above –50°C, in addition to the low-barrier reactions (T) (P), conversion of the seven-membered saturated metal-containing ring and inversion of the tetrahedral configuration of the Ni atom with activation barriers of 48–51 kJ/mole are observed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 327–335, February, 1990.     

New indoline spiropyrans with π-acceptor substituents in the 8′ position

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1700–1701, December, 1990.     

Photochromic and thermochromic spirans

By means of the SCF MO LCAO method in the π-electronic (PPP) and all-valence (CNDO) approximations the electronic structures and spectral characteristics of the valence isomers of 2H-chromenes, thiochromenes, and 1,2-dihydroquinolines have been calculated. On the basis of a consideration of the electronic configuration of various excited states, an explanation has been given of the mechanism of the photochromism of the chromenes and their analogs. A hypothesis has been put forward concerning the possibility of thermochromism in 1,2-dihydronaphthalene. It has been shown that the diffuseness of the long-wave absorption band of the open forms of the compounds investigated is not connected with the existence of several stereoisomers. The influence of the heteroatom and of benzo-fusion on the long-wave absorption has been analyzed. The nature of the electronic transition responsible for the long-wave absorption of the photo-colored forms has been explained.     

Formylation and vinylformylation of 2,3-cycloalkenobenzopyrylium salts

Heating of 2,3-cycloalkenobenzopyrylium salts in acetic anhydride with excess formylating agent (dimethylformamide, formanilide, N-formylmorpholine, and N-phenyl-N-methyl-aminoacrolein) gives monoiminium salts, the hydrolysis of which yields aldehydes or, in the presence of hydrosulfide, thioaldehydes. On treatment with the Vilsmeier complex, 1-methylquinaldinium salts give diiminium salts, which are hydrolyzed to the corresponding aldehydes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 733–736, June, 1971.     

Synthesis, structures, and spectral properties of biomimetic azomethine metal chelates with chromophores CuN2S2, CuN2O2, and CuN2Se2. Crystal structure of bis[4-(benzyl)aldimino-3-methyl-1-phenyl-5-pyrazolothiolato]copper(II)

Copper(II) chelates of composition CuL₂ were synthesized based on 4-aminomethylene derivatives of 5-thiopyrazoles (LH). The complexes were studied by UV, IR, ESR, and EXAFS spectroscopy, magnetochemistry, and X-ray diffraction analysis. The coordination polyhedra in the complexes are pseudotetrahedra or octahedra of the types CuN₂S₂ or CuN₄S₂, respectively, which are distorted due to the Jahn—Teller effect. The UV and ESR spectra of copper chelates with a six-coordinate metallocycle formed by the N and S atoms of the azomethine ligand and the nitrogen atom of the quinoline substituent (R) of the C=N−R fragment are most similar to the spectra observed for metals involved in the active centers of natural metalloenzymes (“blue” copper proteins). Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1891–1896, November, 2000.     

Photo- and thermochromic spirans. 16. 2-Oxo-3-phenyl-5,5-dimethylspiro(1,3-oxazolidine-4,2′-[2h]chromenes)

New spirans of the 5,5-dimethyl-3-phenyl-2-oxazolidone series that display photo-chromic properties in alcohol solutions at -80 °C were synthesized. The photoinduced forms are characterized by the presence of two long-wave absorption bands at 350–420 nm and 500–650 nm. The ¹H and ¹³C NMR spectra were studied. Anisochronicity of the diastereotopic methyl groups of the oxazolidone ring shows up only in the ¹³C NMR spectra.See [1] for communication 15.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1035, August, 1985.