荧光素二苯甲酰酯的晶体结构与水解性质的研究

以荧光素和苯甲酰氯为原料制备了荧光素二苯甲酰酯, 并用X射线单晶法测定了晶体和分子结构。晶体空间群为P21/C, a=0.8459(2), b=1.8221(5),c=1.7491(8)nm; β=103.79(3)°; V=2.618nm3, Z=4。酯水解和酯酶水解实验表明其水解速度明显低于荧光素的二醋酸酯、二丙酸酯、二丁酸酯和二已酸酯。根据酯链上苯环的空间位阻和共轭效应, 以及质谱分析结构对这一特性作了解释。     

Synthesis and structure of tris(4-N,N-dimethylaminophenyl)antimony(V) difluoride, dichloride, and dibenzoate

tris(4-N,N-Dimethylaminophenyl)antimony dichloride (I) was prepared by the reaction of tris(4-N,N-dimethylaminophenyl)antimony with copper dichloride. tris(4-N,N-Dimethylaminophenyl)antimony difluoride benzene disolvate II was synthesized from dichloride I and sodium fluoride in aqueous acetone with the subsequent crystallization from benzene. tris(4-N,N-Dimethylaminophenyl)antimony dibenzoate III was obtained from tris(4-N,N-dimethylaminophenyl)antimony and benzoic acid in the presence of hydrogen peroxide in ether or from silver benzoate and the corresponding dichloride in acetone. According to X-ray studies Sb atoms in two crystallographically independent molecules of dichloride, difluoride benzene solvate, and dibenzoate have the distorted trigonal bipyramide coordination [ClSbCl, FSbF, and OSbO trans angles are 178.12(2)°, 178.57(3)°, 177.30°, and 176.49° respectively). Sb-Cl, Sb-F, and Sb-O interatomic distances are 2.4719(7)-2.505(7); 2.106(4); 2.438(2); 2.1212(13) Å respectively. The oxygen atoms of carbonyl groups of the molecule III (C _2v molecular symmetry) are coordinated to the central atom [Sb-O distance 2.987(1) Å].     

Synthesis of (Z)-stilbendiol dibenzoate by sensitized photooxygenation of 2,3,5,6-tetraphenyl-p-dioxin

Sensitized photooxygenation of 2,3,5,6-tetraphenyl-p-dioxin with singlet and triplet excitable sensitizers yields (Z)-stilbendiol dibenzoate together with benzil. Experimental proofs show that unconnected mechanisms could operate accounting for the 1,2 -diketone and the endiol diester formation.     

Thermodynamic properties of triphenylantimony dibenzoate

The temperature dependence of the heat capacity of triphenylantimony dibenzoate Ph₃Sb(OC(O)Ph)₂ is studied in the range of 6–480 K by means of precision adiabatic vacuum calorimetry and differential scanning calorimetry. The melting of the compound is observed in this temperature range, and its standard thermodynamic characteristics are identified and analyzed. Ph₃Sb(OC(O)Ph)₂ is obtained in a metastable amorphous state in a calorimeter. The standard thermodynamic functions of Ph₃Sb(OC(O)Ph)₂ in the crystalline and liquid states are calculated from the obtained experimental data: C_p^°(T), H°(T)–H°(0), S°(T), and G°(T)–H°(0) for the region from T → 0 to 480 K. The standard entropy of formation of the compound in the crystalline state at T = 298.15 K is determined. Multifractal processing of the low-temperature (T < 50 K) heat capacity of the compound is performed. It is concluded that the structure of the compound has a planar chain topology.     

Tetraphenylbismuth aroxides: Synthesis and structure

Tetraphenylbismuth aroxides Ph4BiOAr (Ar = C₆H₃Cl₂-2,6, C₆H₂(Br₂-2,6)(t-Bu)-4, C₆H₂(Br₂-2,6)(NO₂)-4 · 1/2C₆H₆, C₆H₃(NO₂)₂-2,4, C₆H₂(NO₂)₃-2,4,6) were synthesized in the yield up to 90% by the reaction of pentaphenylbismuth with phenols and triphenylbismuth diaroxides and studied by X-ray diffraction. The Bi atoms of tetraphenylbismuth aroxides have a distorted trigonal-bipyramidal coordination with the axial O atom of the aroxide group. The axial angles CBiO vary from 171.7(2)° to 179.3(3)°. The distances Bi-O change in the interval 2.453(2)–2.925(7) Å depending on the nature of substituents in the aromatic ring of the phenol residue. The increasing distance Bi-O in the series of compounds under study correlates with the tendency of the BiC₄ fragment to form the tetrahedral configuration.     

Bromophosgenite: Synthesis and structure solution

Hydrothermally synthesized lead carbonate Pb₂Br₂(CO₃), a bromine analogue of phosgenite mineral Pb₂Cl₂(CO₃), space group P4/mbm, is structurally studied. A comparison of the bromine and chlorine phosgenite analogues is carried out. It is shown that the structure type of the formula analogues changes when fluorine or oxygen substitutes for their large halogens.     

Acylated benzothiazinesulfoneamides: Synthesis and molecular structure

1,2,3,4,4a,10b-Hexahydro-1,4-methano-6H-dibenzo[c,e]-5,6-thiazine-5,5-dioxide has been converted into the corresponding N-acyl derivatives via the reaction with acid chlorides and anhydrides. X-Ray diffraction data have revealed the presence of an intramolecular С–H···O=S hydrogen bond in the molecules of the obtained compounds.     

Ferrocenyl anthracenes: Synthesis and molecular structure

The synthesis of a series of ferrocenylanthracene derivatives is described, utilising the palladium catalysed coupling reaction of 1,1′-bis(chlorozincio)ferrocene with halo-anthracenes. Bis-1,1′-(9-anthracenyl)ferrocene (1) was characterised by single crystal X-ray diffraction and shows an eclipsed ferrocenyl geometry. X-ray crystallographic studies indicate that there are no clear stacking interactions of either an intra- or intermolecular nature between the anthracenyl rings in the structure. A series of 9- and 10-disubstituted ferrocenylanthracene derivatives has also been prepared. In each case the palladium catalyst (Pd(dppf)Cl₂) is recovered in a modified form, e.g. as the [(dppf)PdBr(9-anthracenyl)] complex in the synthesis of bis-1,1′-(9-anthracenyl)ferrocene. The single crystal X-ray structure of one such palladium complex [(dppf)PdBr-9-(10-chloroanthracenyl)] (15a) has been determined in a case where chloride/bromide exchange had occurred in the palladium complex intermediate. The potential application of compound 1 as synthon for the construction of a molecular sensing device is discussed. Cyclic voltammetry and fluorescence studies have been carried out for selected derivatives.     

4-Dimethylaminoacetophenone O-vinyloxime: Synthesis and steric structure

4-Dimethylaminoacetophenone oxime was synthesized from 4-dimethylaminoacetophenone and hydroxylamine hydrochloride. Its reaction with acetylene in the system KOH-DMSO gave previously unknown 4-dimethylaminoacetophenone O-vinyloxime as the major product. According to the experimental data and quantum-chemical calculations, 4-dimethylaminoacetophenone O-vinyloxime is formed as the only E isomer with preferential s-trans conformation of the vinyloxy group, which is characterized by essentially nonplanar structure.     

3,3,3-Tribromo-1-nitropropene: Synthesis and structure

3,3,3-Tribromo-1-nitropropene and its precursors such as 2-hydroxy- and 2-acetoxy-1,1,1-tribromo-1-nitropropanes were prepared and characterized by IR, UV, ¹H, ¹³C, HMQC, and HMBC NMR spectroscopy methods. Structure of tribromomethylnitroalkene was studied by X-ray diffraction.     

New spiro-fused 2-nitrocyclopropanecarboxylates: Synthesis and structure

Reactions of alkyl 3-bromo-3-nitroacrylates with cyclic CH-acids, Meldrum’s acid or 3-methyl-1-phenylpyrazol-5-one, afford new spiro-fused 2-nitrocyclopropanecarboxylates. In the case of Meldrum’s acid, the products are formed as individual diastereomers. The obtained experimental results are confirmed by quantum chemical calculations (B3LYP/6-311+G(d,p) taking into account solvent effects).     

Tetra- and triarylantimony pentafluoroand pentachlorophenoxides: Synthesis and structure

2,3,4,5,6-Pentafluorophenoxytetraphenylantimony (I), 2,3,4,5,6-pentachlorophenoxytetraphenylantimony (_II), 2,3,4,5,6-pentafluorophenoxytetra-p-tolylantimony (III), and 2,3,4,5,6-pentachlorophenoxytetra-p-tolylantimony (IV) were synthesized by the reaction of pentaarylantimony (Ar = Ph, p-Tol) with pentafluoro- and pentachlorophenol in toluene. Compounds I–IV were also synthesized with yields of up to 95% from pentaarylantimony and triarylantimony diaroxides. Triarylantimony diaroxides Ph₃Sb(OC₆F₅)₂ (V), Ph₃Sb(OC₆Cl₅)₂ (VI), p-Tol₃Sb(OC₆F₅)₂ (VII), p-Tol₃Sb(OC₆Cl₅)₂ (VIII) were synthesized from triarylantimony, tert-butylhydroperoxide, and phenol in ether. The Sb atoms in compounds I–VIII had a distorted trigonal bipyramidal coordination with electronegative ligands in axial positions.     

Gradient copolymers: Synthesis,structure, and properties

Conditions of formation of gradient copolymers characterized by a continuous change in composition along each chain and methods of their synthesis by living ionic and pseudoliving radical polymerizations are considered. Characteristics, structure, and physicochemical properties of gradient copolymers are discussed.     

Functionalized pentamethylferrocenes: Synthesis, structure, and electrochemistry

The advantageous properties of the Cp^* ligand — intensified electron donation, steric bulk, and enhanced solubility in comparison to the ubiquitous Cp ligand — are finding increasing use in organometallic chemistry. A systematic evaluation of synthetic routes to pentamethylferrocene compounds with a wide range of functionalities, including carboxyl, carbonyl, aminomethyl, vinyl, ethynyl, fulvenyl, cyclopentadienylmethyl, and others is reported. Spectroscopic, structural, and electrochemical properties of such functionalized pentamethylferrocenes Fc^*/2—R are compared to those of non-methylated ferrocenes Fc—R. The electronic influence of the Cp^* ligand in these unsymmetricalferrocenes Fc^*/2—R has been studied by cyclic voltammetry measurements, demonstrating a decrease in oxidation potential of −0.276 V in direct comparison to non-methylated ferrocenes Fc—R.     

New fluorochromatouranylates of alkali metals: Synthesis and structure

Four new fluorochromatouranylates, namely, K[UO₂(CrO₄)F] · 1.5H₂O (I), Rb[UO₂(CrO₄)F] · 1.5H₂O (II), Rb[UO₂(CrO₄)F] · 0.5H₂O (III), and Cs[UO₂(CrO₄)F] · 0.5H₂O (IV), have been synthesized, and their crystallographic characteristics have been determined. All the compounds crystallize in monoclinic system, space group P2₁/c, with the unit cell parameters a = 13.1744(5) Å, b = 9.4598(3) Å, c = 13.0710(4) Å, β = 103.746(1)°, Z = 4, R = 0.0235 (I); a = 13.5902(7) Å, b = 9.5022(4) Å, c = 13.2271(6) Å, β = 102.914(2)°, Z = 4, R = 0.0247 (II); a = 24.7724(8) Å, b = 12.6671(4) Å, c = 9.4464(3) Å, β = 97.661(1)°, Z = 8, R = 0.0448 (III); a = 25.725(1) Å, b = 12.8261(5) Å, c = 9.4929(4) β = 97.208(1)°, Z = 8 (IV). The pairs of compounds I and II and compounds III and IV are isostructural. Crystals of compounds I–III have been subjected to complete X-ray diffraction study. It has been established that the structures of compounds I–III are built of [UO₂(CrO₄)F] _n ^n? layers, which are parallel to the (100) plane and linked into a framework by alkali-metal cations located between layers, together with water molecules. The effect of topological and geometric isomerism on the structural features of 34 known uranyl compounds of the AT³M² crystallochemical group, to which the studied compounds I–III also belong, is discussed.     

Synthesis and structure of diphospholenebutadienes

Conclusions A method was developed for the synthesis and purification of 2,3-bis(1-oxophospholen-1-yl)-1,3-butadienes, which were identified via the IR and PMR spectra.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1144–1146, May, 1981.The authors thank N. V. Teptin, T. A. Zyablikov, and É. I. Gol'dfarb for recording the indicated spectra.