O. S. Filipenko

Influence of the cation on the properties of binuclear iron nitrosyl complexes. Synthesis and crystal structure of [Pr4 nN]2[Fe2S2(NO)4]

The binuclear nitrosyl complexes Q2[Fe2S2(NO)4], where Q=Me, Et, Prn, and Bun, were synthesized. The crystals of [Pr4nN]2Fe2S2(NO)4 were studied by X-ray analysis. The influence of the cation size on the electronic structure and symmetry of its local environment in the synthesized complexes was examined. The decrease in the isomeric shifts in the57Fe Mössbauer spectra is related to the increase in the length of the alkyl substituent chain of the quaternary tetraammonium cation and is consistent with changing the structural parameters: a decrease in the bond angle of the Fe−NO bond and stretching vibrations of the NO groups due to changes in intermolecular contacts.

Specific Structural Features and Photochemical Properties of Three Benzo-Annulated 2,2-Diphenyl[2H]chromenes

The crystal structures of 3,3-diphenylbenzo[f]-chromene, C 25 H 18 O, 1,3,3-triphenylbenzo[f]chromene, C 31 H 22 O, and 2,2-diphenylbenzofuro[2,3-g]chromene, C 27 H 18 O 2 , have been determined. Annulated 2,2-di- phenylchromenes are of interest because of the influence of steric strain energy in the pyran ring on the photochromic properties of these compounds.

STRUCTURES AND PHOTOCHROMIC PROPERTIES OF SUBSTITUTED SPIROINDOLINONAPHTHOXAZINES

Six indolinospironaphthoxazines were studied by X-ray diffraction analysis. It was demonstrated that the electronic nature of the substituents in the naphthoxazine and indoline fragments has no substantial effect on the Cspiro−O and Cspiro−N bond lengths. Photocolorability of the compounds under study depends only slightly on the abovementioned bond lengths and correlates mainly with the energy of steric strain of the oxazine ring. The stability of the open forms of spiroindolinonaphthoxazines that formed upon photoirradiation is determined to a large extent by the electronic and steric nature of the substituents. The exception is the compound that contains the NO2 group in the indoline fragment. In the last-mentioned case, the cleavage of the ring occurs through a substantially different pathway.

Molecular structure of 1′,3′,3′-trimethyl-6-trifluoromethylsulfonyl-spiro-(indoline-2,2′-benzo[b]pyran)

Photochromic 1′, 3′, 3′ -trimethyl-6-trifluoromethylsulfonyl-spiro(indoline-2,2′-ben-zo[b]pyran) (1) was studied by X-ray diffraction analysis. In compound1, the Cspiro-O bond (1.49(1) Å (average)), broken on photoexcitation, is the longest of all the indoline spiropyrans studied.

Crystal Structure of a Mixed-Valence Hydroxonium Cerium Sulfate Hydrate

The structures of two orthorhombic modifications ( α and β ) and the structure and proton conductivity of the monoclinic γ modification of Ce 4+ sulfate tetrahydrate Ce(SO 4 ) 2 · 4H 2 O have been studied [1–3]. Their crystal structures consist of neutral ëe(H 2 O) 4 (SO 4 ) 2 layers; the coordination polyhedra of cerium atoms are square antiprisms [1–3]. We obtained crystals of unknown composition when studying the conditions for crystallization of the γ modification, whose tabular crystals make up the major fraction of analytical-grade Ce(SO 4 ) 2 · 4H 2 O powder. X-ray crystallographic study has shown that these new crystals belong to a new block-layered structural type. The structure and composition of the first mixed valence cerium sulfate hydrate of

Structural-chemical transformations during organic self-propagating high-temperature synthesis. Crystal structure of piperazine malonate and its crystal hydrate

An organic salt, piperazine malonate, was prepared by self-propagating high-temperature synthesis (SHS) in a solid-phase piperazine-malonic acid (P-M) system. Triclinic crystals of piperazine malonate (PM) hydrate (I) were isolated from an aqueous solution. Monoclinic crystals of anhydrous piperazine malonate (2) were isolated from a solution in DMSO. Crystals 1 and 2 were studied by X-ray structural analysis. Structures 1 and 2 consist of centrosymmetrical piperazinium cations, which are linked to anions of malonic acid through N−N…O hydrogen bonds. In structure 1, the anion is asymmetrical. The angle between the planes of the carboxyl groups and the plane of the CH2 groups are 29. 2° and 99.9°. In structure 2, the anion is located on a twofold axis, and the corresponding angles are 81.5°. The N…O distances are in the range of 2.691(4)–2.838(5) Å.

Photochemical properties and structures ofN-amino andN-azomethine derivatives of 2,4,6-triphenylpyridinium perchlorates

The molecular structures of the initial compounds and the products of photocyclization involving amino and azomethine groups in perchlorates ofN-amino (1) andN-azomethine (2) derivatives of 2,4,6-triphenylpyridinium cations were studied. Cations1 and2 have an essentially non-coplanar arrangement of the α-Ph rings, and the product of photocyclization of2, cation3, is characterized by a flattened structure. It was found that the orientation of the lone electron pair of the N atom with respect to one of the planes of the α-Ph rings in molecule1 is more favorable for monocyclization involving the amino group. The structure of molecule2 allows two routes of the photoreaction,viz., O → N proton transfer and monocyclization with an α-Ph ring. However, the structural features of molecule2 are more favorable for photocyclization.

The unusual structure of 3-hydro-2-acetylbenzo[b]thiophene hydrazones

The structure of N,N-disubstituted 3-hydroxy-2-acetylbenzo[b]thiophene hydrazones was investigated by x-ray structural analysis. 2-(N-Methyl-N-phenylhydrazinoethylidene)-3(2H)-benzo[b]thiophenone exists in the E-ketoenehydrazine form, and 2-(N,N-diphenylhydrazinoethylidene)-3(2H)-benzo[b]thiophenone in the crystals forms a structure intermediate between the ketoenehydrazine and hydroxyhydrazone forms.

Low-temperature study of the molecular and crystal structures of 2-(2′-tosylamino-5′-nitrophenyl)-4H-3,1-benzoxazin-4-one, an organic luminophore

The crystal structure of 2-(2′-tosylamino-5′-nitrophenyl)-4H-3,1-benzoxazin-4-one (I) is studied by X-ray diffraction at 100 K (C21H15N3O6S, a = 20.899(2) Å, b = 10.948(1) Å, c = 8.260(1) Å, V = 1889.3(1) Å3, Z = 4, and space group Pbn21). The compound exhibits an anomalous Stokes shift. Upon cooling, the oxazineaminophenyl fragment of compound I acquires a quinoid structure and the linear parameters of the intramolecular N-H⋯N hydrogen bond increase (the distance between the heterocyclic nitrogen atom and the hydrogen atom of the tosylamino group becomes 1.92 Å). The complete optimization of the geometry of molecules in compound I and unsubstituted 2-(2′-tosylaminophenyl)-4H-3,1-benzoxazin-4-one in the ground singlet electronic state is performed by the semiempirical method with the MOPAC program. It is shown that the oxygen atoms in the sulfo group of molecule I are nonequivalent, because one of them is involved in the intermolecular C-H⋯O hydrogen bond.

Effect of the type of linkage between phenyl groups on the structure and photochemical properties of 2,2-diaryl-substituted pyridoannelated [2H]-chromenes

Three 2,2-diaryl-substituted pyridoannelated [2H]-chromenes have been studied by X-ray diffraction analysis. Bonding of the benzene rings through bridges of different nature and with different length affects substantially the orientation of the benzene rings, steric interactions at the C center, the conformation of the molecule, and the C−O bond length. A correlation between the photocolorability of chromenes under study and the orientation of the benzene rings with respect to the C−O bond, which provides different prerequisites to stabilization of the C(1)-centered, cation formed upon cleavage of the C−O bond, was established. The effect of the orientation of the benzene rings on the dark reaction of ring closure was found.