2-氨基-5-硝基吡啶乙酸根桥联双核铜配合物的合成和晶体结构

2-氨基-5-硝基吡啶与Cu(CH3COO)2反应生成一个新的乙酸根桥联的双核铜配合物[Cu(CH3COO)2(C5H5N3O2)]2.2H2O.该配合物中,铜原子与一个吡啶环上N原子和四个乙酸根上O原子配位形成五配位的四方锥构型.其晶胞参数为:单斜晶系,空间群P21/c,a=0.834 5(8),b=2.001(2),c=0.808 1(8)nm,β=96.734(4)°,V=1.340(2)nm3,Z=2,Mr=657.37,Dc=1.629 g/cm3,F(000)=652,μ=1.663 mm-1,R1=0.060 4,wR2=0.126 4.电子吸收光谱在207 nm处有吸收;电子发射光谱在419 nm处有发射峰.并用IR和元素分析对配合物进行了表征.     

2-氨基-3-硝基吡啶和2-氨基-5-硝基吡啶的CI-MS-MS分析

二氨基-3-硝基吡啶和2_氨基-5-硝基吡啶的EI—MS质谱图接近，单纯通过Ⅱ-MS质谱图较难区分这两种异构体，作者以甲烷为反应气对2-氨基-3-硝基吡啶和2-氨基-5-硝基吡啶进行化学电离，并利用离子阱质谱的串联质谱技术在离子阱内以He作碰撞气进行碰撞诱导裂解，所得的CI—MS—MS质谱图表明，两者之间存在明显的差别，可用于2-氨基-3-硝基吡啶和2-氨基一5一硝基吡啶的鉴别。     

2-氨基-3-硝基吡啶和2-氨基-5-硝基吡啶的EI/MS/MS分析

2 氨基 3 硝基吡啶和2 氨基 5 硝基吡啶的一级质谱图接近,单纯通过一级质谱图较难区分这两种异构体,利用离子阱质谱的串联质谱技术对2 氨基 3 硝基吡啶和2 氨基 5 硝基吡啶在离子阱内以He作碰撞气进行碰撞诱导裂解,所得的二级质谱图表明,两者之间存在明显的差别,可用于2 氨基 3 硝基吡啶和2 氨基 5 硝基吡啶的鉴别。     

Crystal structure, spectroscopic, and theoretical investigations of excited-state proton transfer in the doubly hydrogen-bonded dimer of 2-butylamino-6-methyl-4-nitropyridine N-oxide

The crystal structure of 2-butylamino-6-methyl-4-nitropyridine N-oxide (2B6M) was resolved on the basis of X-ray diffraction. Solid 2B6M occurs in the form of a doubly hydrogen-bonded dimer with squarelike hydrogen-bonding network composed of two intra- (2.556(2) A) and two intermolecular (2.891(2) A) N-H...O type hydrogen bonds. The molecule thus has both a protonable and a deprotonable group that led us to investigate the possibility of an excited-state proton transfer (ESIPT) reaction in different solvents by means of experimental absorption, steady state, and time-resolved emission spectroscopy. The results were correlated with quantum mechanical TD-DFT and PM3 calculations. Experimental and theoretical findings show the possibility of an ESIPT reaction in polar solvents. It is demonstrated that in particular the emission spectra of 2B6M are very sensitive to solvent properties, and a large value of the Stokes shift (about 8000 cm(-1)) in acetonitrile is indicative for an ESIPT process. This conclusion is further supported by time-resolved fluorescence decay measurents that show dual exponential decay in polar solvents. Vertical excitation energies calculated by TD-DFT reproduce the experimental absorption maxima in nonpolar solvents well. The majority of electronic transitions in 2B6M is of pi --> pi* character with a charge shift from the electron-donating to the electron-accepting groups. The calculations show that, due to the charge redistribution on excitation, the acidity of the amino group increases significantly, which facilitates the proton transfer from the amino to the N-oxide group in the excited state.     

Electronic spectra and structure of methyl derivatives of 4-nitropyridine N-oxide

The UV spectra of seven methyl derivatives of 4-nitropyridine N-oxide in ethanol have been examined. The electronic spectra were calculated by a modified INDO method. Transition energies, intensities and assignments were compared with UV spectra. Spectroscopic manifestations of intramolecular interaction indicate that methyl groups modify the electronic interaction between the N-oxide and NO₂ groups mainly through a steric strain.Department of Organic Chemistry, University of Economics, Pl-53342 Wroclaw, Poland. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 786–793, June, 2000.     

Crystal structure of potassium 2-thiobarbiturate

The crystal and molecular structure of potassium thiobarbiturate C₄H₃KN₂O₂S (C₄H₄N₂O₂S-2-thiobarbituric acid, H₂TBA) is determined. Crystallographic data for KHTBA are as follows: a = 11.2317(17) Å, b = 3.8687(6) Å, c = 14.557(2) Å, β = 97.448(4)°, V = 627.18(17) ų, space group P2/c, Z = 4. Each potassium ion is linked with four oxygen atoms and two S atoms forming a distorted octahedron. N-H…O and C-H…S hydrogen bonds form a branched three-dimensional network. The structure is also stabilized by the π-π interaction of heterocyclic HTBA^? ions.     

2-氨基-6-甲氧基-3-硝基吡啶的合成

以2-氯-5-硝基吡啶为原料,经甲氧基化反应得2-甲氧基-5-硝基吡啶(2),2再与液氨/高锰酸钾进行氨化反应制得2-氨基-6-甲氧基-3-硝基吡啶,总收率77%。     

Crystal and molecular structure of 2-methylbenzimidazole

All-Union Scientific-Research Institute for Chemical Reagents and Ultrapure Substances. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 3, pp. 121–122, May–June, 1991.     

Crystal structure of BiNbTe2O8

BiNbTe₂O₈ crystallises with orthorhombic symmetry (space group Pbca) and unit cell parameters: a=5.6109(7) Å, b=8.1277 (8) Å, c=31.205 (3) Å, Z=8. Its crystal structure has been solved from single crystal X-ray diffraction data and refined to a final reliability factor R1=0.0512. It can be described as a regular succession along [001] of ReO₃-like sheets of NbO₆ octahedra, and fluorite-like sheets of BiO₈ distorted cubes and Te(1)O₄ disphenoı̈ds. These sheets are connected by Te(2)O₃ pyramids via Nb–O(4)–Te(2)–O(8)–Bi bridges. The lone pairs of Te(1) and Te(2) atoms are stereochemically active and point toward the empty cuboctahedral sites of the ReO₃-like sheets.     

Crystal and molecular structure of 2-ferrocenyl-2-propanol

The crystal and molecular structure of 2-ferrocenyl-2-propanol is studied by means of physicochemical methods. The compound crystallizes in the form of three crystallographically independent molecules with slightly different conformations. Crystals are monoclinic, C₁₃H₁₆FeO: a = 6.2687(7) Å, b = 36.614(4) Å, c = 15.291(2) Å; β = 97.86(2)°; V = 3477.2(7) ų, Z = 12, d x = 1.396 g/cm³, P2₁/n space group. The molecule consists of the ferrocene fragment and the isopropyl carbinol substituent.     

Crystal structure of the oxime of 2-acetylpyridine

Institute of Chemical Physics, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 3, pp. 113–115, May–June, 1991.