Crystal and molecular structures of binuclear caesium complexes with 1,3-calix[4]-bis-crown-6 and 1,3-calix[4]-bis-benzo-crown-6

The crystal structures of two binuclear complexes between caesium and 1,3-calix[4]-bis-crowns have been determined. Cs₂ Bis-benzoC6(NO₃)₂. 3CHCl₃ (1) in whichBis-benzoC6 is 1,3-calix[4]-bis-benzo-crown-6, crystallizes in the orthorhombic system: space groupPca2 ₁ a=19.513(10),b=15.382(5),c=23.708(9) Å,V=7116(5) ų,Z=4. Refinement led to a final conventionalR value of 0.065 for 2321 reflections. The structure of (1) is analogous to those already reported withBis-C6, (in whichBis-C6 is, 1,3-calix[4]-bis-crown-6) and NO ₃ ^– as a counter-ion. Cs₂ Bis-C6(NCS)₂ (2) crystallizes in the monoclinic system: space, groupC2 a=36.57(2),b=11.47(1),c=13.65(1) Å, =109.03(5)°.,V=5415(6) ų,Z=4. Refinement led to a final conventionalR value of 0.063 for 2227 reflections. Compound (2) is made of dimers bridged by a disordered NCS^– ion. The crown ether chain conformations are discussed. Supplementary data relating to this article (atomic coordinates, anisotropic displacement parameters, bond distances and angles and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82199 (52 pages).     

Ein neues Samariumnitridsulfid: Sm4N2S3

A New Samarium Nitride Sulfide: Sm₄N₂S₃ The oxidation of samarium with sulfur in the presence of SmCl₃ and NaN₃ as nitrogen source (molar ratio: 12:9:4:2, evacuated silica vessel, some NaCl as flux, 850°C, 7 d) yields Sm₄N₂S₃ as lath-shaped, dark red single crystals. The by-products (NaCl and NaSm₂Cl₆) are rinsed with water from the crude product. The crystal structure of Sm₄N₂S₃ (monoclinic, C2/m (no. 12), Z = 2, a = 1 318.04(12), b = 391.57(2), c = 1 031.76(9) pm, β = 130.874(6)°, R = 0.036, R_w = 0.031) contains two crystallographically different Sm³⁺, both in sixfold coordination of the anions. Besides distorted octahedra [(Sm1)N₃S₃] and [(Sm2)NS₅], tetrahedra [(N^3?)(Sm)] connected via two cis-oriented edges to form chains [N(Sm1)_3/3(Sm2)_1/1]³⁺ build up the Mayn structural feature. These are arranged in the fashion of a closest packing of rods and held together by two crystallographically different S^2? anions which take care for charge neutrality and three-dimensional interconnection.     

Das erste Diniobat mit ‚isolierten’︁ Anionen: KLi4[NbO5]=K2Li8[Nb2O10]

The First Diniobate with ‘Isolated’ Anions: KLi₄[NbO₅]=K₂Li₈[Nb₂O₁₀] [1] . By heating of well ground mixtures of the binary oxides [K₂O, Li₂O, Nb₂O₅, K:Li:Nb=1.1:4.4:1, Pt-tube, 1100°C, 3d] colourless, triclinic single crystals of KLi₄NbO₅ have been prepared for the first time: space group P1 (Nr. 2) with a=816.9(2) pm, b=592.2(2) pm, c=589.7(2) pm, α=121.00(2)º, β=91.78(2)°, γ=99.23(2)°, Z=2. The crystal structure was solved by four-cycle diffractometer data [Mo-Kα , 1386 from 1386 I_o(hkl), R=3.4%, R_w=2.6%], parameters see text. Characteristic for this structure are “isolated” groups of [Nb₂O₁₀] and the tetrahedral coordination of Li(1), Li(2), and Li(3). Li(4) has a tetragonal-pyramidal coordination. The structural relations are deduced by Schlegel Diagrams. The Madelung Part of Lattice Energy, MAPLE, the Effective Coordination Numbers, ECoN and the charge distribution have been calculated and discussed.     

Zinc(II) Hydration in Aqueous Solution: A Raman Spectroscopic Investigation and An ab initio Molecular Orbital Study of Zinc(II) Water Clusters

Raman spectra of aqueous Zn(II)–perchlorate solutions were measured over broad concentration (0.50–3.54 mol-L^–1) and temperature (25–120°C) ranges. The weak polarized band at 390 cm^–1 and two depolarized modes at 270 and 214 cm^–1 have been assigned to ₁(a _1g), ₂(e _g), and ₅(f _2g) of the zinc–hexaaqua ion. The infrared-active mode at 365 cm^–1 has been assigned to ₃(f _1u). The vibrational analysis of the species [Zn(OH₂) ₂ ⁺ ] was done on the basis of O _h symmetry (OH₂ as point mass). The polarized mode ₁(a _1g)-ZnO₆ has been followed over the full temperature range and band parameters (band maximum, full width at half height, and intensity) have been examined. The position of the ₁(a _1g)-ZnO₆ mode shifts only about 4 cm^–1 to lower frequencies and broadens by about 32 cm^–1 for a 95°C temperature increase. The Raman spectroscopic data suggest that the hexaaqua–Zn(II) ion is thermodynamically stable in perchlorate solution over the temperature and concentration range measured. These findings are in contrast to ZnSO₄ solutions, recently measured by one of us, where sulfate replaces a water molecule of the first hydration sphere. Ab initio geometry optimizations and frequency calculations of [Zn(OH₂) ₂ ⁺ ] were carried out at the Hartree–Fock and second-order Møller–Plesset levels of theory, using various basis sets up to 6-31 + G*. The global minimum structure of the hexaaqua–Zn(II) species corresponds with symmetry T _h. The unscaled vibrational frequencies of the [Zn(OH₂) ₂ ⁺ ] are reported. The unscaled vibrational frequencies of the ZnO₆, unit are lower than the experimental frequencies (ca. 15%), but scaling the frequencies reproduces the measured frequencies. The theoretical binding enthalpy for [Zn(OH₂) ₂ ⁺ ] was calculated and accounts for ca. 66% of the experimental single-ion hydration enthalpy for Zn(II).Ab initio geometry optimizations and frequency calculations are also reported for a [Zn(OH₂) ₂ ¹⁸ ] (Zn[6 + 12]) cluster with 6 water molecules in the first sphere and 12 in the second sphere. The global minimum corresponds with T symmetry. Calculated frequencies of the zinc [6 + 12] cluster correspond well with the observed frequencies in solution. The ₁-ZnO₆ (unscaled) mode occurs at 388 cm^–1 almost in perfect correspondence to the experimental value. The theoretical binding enthalpy for [Zn(OH₂) ₂ ¹⁸ ] was calculated and is very close to the experimental single ion-hydration enthalpy for Zn(II). The water molecules of the first sphere form strong hydrogen bonds with water molecules in the second hydration shell because of the strong polarizing effect of the Zn(II) ion. The importance of the second hydration sphere is discussed.     

Stereoselective synthesis of (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone

A stereoselective synthesis of the pentaketide lactone (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone has been achieved.     

Condensed tetrazolo-1,3,5-triazines. 4. Synthesis of salts of 5-aminotetrazolo[1,5-a]-1,3,5-triazin-7-one

2-Amino-4-azido-1,3,5-triazin-6(1H)-ones were synthesized by successive substitution of the trinitromethyl groups in 2-amino-4,6-bis(trinitromethyl)-1,3,5-triazines under the influence of azide and nitrite ions. Interaction of 2-amino-4-azido-1,3,5-triazin-6(1H)-ones with bases led to the azido-tetrazole tautomeric conversion give salts of 5-aminotetrazolo[1,5-a]-1,3,5-triazin-7-one. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1211–1219, August, 2006.     

5，10，15，20-四 [4-(4''-乙基哌嗪基)苯基]卟啉的合成及其与DNA的相互作用

基于卟啉对癌细胞的特殊亲和作用和哌嗪化合物的抗肿瘤、抗病毒作用，设计并合成了具有哌嗪结构的新型卟啉化合物5，10，15，20-四[4-(4'-乙基哌嗪基)苯基]卟啉（TEPPPH₂），其结构经UV-Vis, 元素分析，¹H NMR等手段证明。采用UV-Vis光谱和荧光光谱研究了TEPPPH₂和小牛胸腺DNA 的相互作用模式和结合机理。实验发现，TEPPPH₂能嵌入到DNA的碱基对中，1个小牛胸腺DNA分子对TEPPPH₂分子的最大结合数n约为88，结合常数为8.4×10⁶mol•L^-1 。TEPPPH₂与DNA的结合数和结合常数大于已知的四（4-N-甲基吡啶基）卟啉和Ca/sal-his、Ni/sal–aln型席夫碱抗癌药物。     

Intramolecular cyclization of 5-aryl-3-arylamino-4-benzoyl-1h-3-pyrrolin-2-ones to pyrrolo[3,4-<Emphasis Type="Italic">b</Emphasis>]quinolines

It has been shown that 5-aryl-3-arylamino-4-benzoyl-1H-3-pyrrolin-2-ones cyclize in the presence of conc. H₂SO₄ to give pyrrolo[3,4-b]quinolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1543–1545, October, 2004.     

A sol-gel route for the development of rare-earth aluminum borate nanopowders and transparent thin films

A new sol-gel route was applied to obtain Y_0.9Er_0.1Al₃(BO₃)₄ crystalline powders and amorphous thin films by using Al(acac)₃, B(OPrⁱ)₃, Y(NO₃)₃·6H₂O, and Er(NO₃)₃·5H₂O as starting materials dissolved in propionic acid and ethyl alcohol mixtures. Our study shows that propionic acid acts as good chelant agent for yttrium and erbium ions while ethyl alcohol allows to dissolve Al(acac)₃. This process makes the resulting sols very stable to obtain homogeneous gels and transparent amorphous thin films. In addition, the propionic acid prevents the sol precipitation, making easy porous- and crack-free thin film depositions. Chemical reactions involved in the complexation were discussed. As-prepared powders and films are amorphous and present a good thermal stability due to their high glass transition (746 °C) and crystallization temperatures (830 °C). This new sol-gel route showed to be adequate to obtain dense and crack-free thin films free of organic and hydroxyl groups that can be considered as promising materials to be used in integrated optical systems.