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The results of a single-crystal X-ray diffraction analysis of fluorene, 9-fluorenone, and 9-dicyanomethylenefluorene derivatives as individual compounds, as well as their crystal solvates, molecular complexes, and charge-transfer complexes, are generalized. The most interesting features of the molecular geometry and conformation and the molecular packing in the crystals are discussed. The structural formula of 95 compounds and the R factors for X-ray diffraction analysis, which characterize the reliability of determining the structure, are summarized in three tables.

This paper generalizes the results of the X-ray structure investigations of crystals of the 1,3-indandione and 1,3-dicyanomethyleneindan derivatives (primarily, individual compounds, as well as crystal hydrates, crystal solvates, ionic salts, and betaine-like intraionic derivatives of 1,3-indandione). The structural features of molecules and crystals, the geometric parameters, and the intramolecular and intermolecular hydrogen bonds are discussed. Structural formulas of 92 compounds and selected geometric parameters of molecules and hydrogen bonds are presented in six tables.

The results of X-ray structure investigations of crystalline compounds with a tricyanovinyl group (individual substances, molecular complexes, and ionic salts) and related compounds are generalized. The most interesting geometric and conformational characteristics of the molecules and ions are discussed. Consideration is given to the crystal chemical features of the compounds involved. The structural formulas of 73 compounds and the reliability factors (R factors) of crystal structure determination are given in the tables.

The results of a single-crystal X-ray diffraction analysis of fluorene, 9-fluorenone, and 9-dicyanomethylenefluorene derivatives as individual compounds, as well as their crystal solvates, molecular complexes, and charge-transfer complexes, are generalized. The most interesting features of the molecular geometry and conformation and the molecular packing in the crystals are discussed. The structural formula of 95 compounds and the R factors for X-ray diffraction analysis, which characterize the reliability of determining the structure, are summarized in three tables.

Heating 3,8-dinitro-10-carboxy-6H-dibenzo[b,d]pyran-6-one in DMSO, DMF, or HMPTA leads to decarboxylation and the replacement of the carboxyl group by a hydroxy group with the formation of 3,8-dinitro-6H-dibenzo[b,d]pyran-6-one and 3,8-dinitro-10-hydroxy-6H-dibenzo [b,d]pyran-6-one. The decarboxylation of 2,7-dinitro-5,10-dioxo-4,5,9,10-tetrahydro-4,9-dioxapyrene in HMPTA is preceded by opening of the two lactone rings and the formation of a 1:4 molecular complex of 4,4′-dinitro-6,6′-dihydroxy-2,2′-dicarboxybiphenyl with HMPTA, whose structure was established by x-ray diffraction structural analysis.

Treatment of 2,4,8,10-tetranitro-6(5H)-phenanthridinone with hexamethylphosphoric triamide leads to intermolecular nucleophilic substitution of the nitro group by a hydroxy group, the source of which is the water contained in the solvent, to give 10-hydroxy-2,4,8-trinitro-6(5H)-phenanthridinone. An intramolecular interaction with the participation of a proton of the aromatic ring and an oxygen atom of the hydroxy or acetoxy group of the 10-hydroxy- or 10-acetoxy-2,4,8,-trinitro-6(5H)-phenanthridinone, the properties of which are characteristic for an intramolecular hydrogen bond, was detected by x-ray diffraction analysis and PMR spectroscopy.

Using x-ray structural analysis we determined the structure of two crystal solvates with benzene: 2',4,4',6-tetranitro-2-carboxybiphenyl (composition 2:3, space group PI, Z = 2, 1464 reflections, R = 0.054) and 2'-nitro-2-carboxylphenyl (composition 2:1 space group P21/b, Z = 4, 1309 reflections, R = 0.030). The angles between the planes of the benzene rings and the acid molecules are 80.2 and 78.6 ~ . In the crystal the acidic molecules are joined into centrosymmetric dimers by carboxylcarboxyl hydrogen bonds (OH...O 2.687 and 2,635 ~). The benzene molecules atthe centers of symmetry are distributed between the eight-membered H-rings. The solvate benzene molecule in the general position is disordered.

By X-ray structural analysis of the complexes of pyromllitdianilic acid with amide solvents it was found that the character of the system of hydrogen bonds and the structure of the solvates depend on the nature of the amide solvent. It was shown that in the case of polyamic acid solvates, the hydrogen bonds formed in the solid polyamic acid films can be studied by mass-spectrometric thermal analysis; from the obtained data, the mechanism may be determined of the function of additives catalyzing the solid phase cyclodehydration of polyamic acids.

An x-ray diffraction structural analysis was carried out on the molecular comO plex C:~H6N~OIo-C=H6OS (a = 11.282, b = 21.866, c = 7.836 A, y = 99.32 ~ space group P2~/n, Z = 4. The study was carried out on a diffractometer to record 1893 reflections. The direct method was used to give R = 0.033. The 2',4,4',6tetranitro-2-carboxydiphenyl and dimethylsulfoxide molecules in the crystal a~e connected in pairs to form a strongly hydrogen-bonded complex (OH...O, 2.494 A). The position of the hydrogen atom and the change in the geometry of the carboxyl group and the dimethylsulfoxide molecule indicate partial ionic character of the molecules in the complex. The dihedral angle between the phenyl ring planes in the diphenyl derivative is 84.8 ~ and the twist of the ortho NO2 group from the corresponding phenyl ring is 6.8 ~ and the twist of the ortho C02H group is 40.3 ~ .