Band 57, Heft 2

Europium selenogermanate(IV) and Europium selenogermanate(III) were synthesized by direct reactions of the elements at 1023 K and their crystal structures determined by single crystal methods. α-Eu 2 GeSe 4 (P21, a = 6.964(1), b = 7.055(2), c = 8.400(2) Å , β = 108.12(2)˚, Z = 2) crystallizes as a polar variant of the monoclinic Sr 2 GeS 4 -type at room temperature. At 673 K, the structure is centrosymmetric (β-Eu 2 GeSe 4 , P2 1 /m, a = 6.969(1), b = 7.059(2), c = 8.516(2)Å , β = 107.99(2)˚, Z = 2), and a phase transition P2 1 →P2 1 /m as known from Eu 2 GeS 4 is highly probable. Eu 2 Ge 2 Se 5 (P2 1 /n, a = 8.421(4), b = 12.235(4), c = 9.127(3) Å,β = 93.67(4)˚, Z = 4) crystallizes in the Sr 2 Ge 2 Se 5 type, mainly characterized by complex [Ge 4 Se 10 ] 8- anions with homonuclear Ge-Ge bonds. Both compounds are deep red Zintl phases according to (Eu 2+ ) 2 Ge 4+ (Se 2- ) 4 and (Eu 2+ ) 2 (Ge 3+ ) 2 (Se 2- ) 5 . Magnetic susceptibility measurements show paramagnetic behavior above 20Kwith magnetic moments of 8.00(5) μB/Eu and 8.10(5) μB/Eu, respectively, indicating Eu 2+ . Eu 2 Ge 2 Se 5 orders antiferromagnetically at T N = 4.2(2) K and undergoes a metamagnetic transition at 2 K at a critical field of 0.5(3) T. The saturation moment at 2.2 K and 5.5 T is 7.00(2) μB/Eu. Eu 2 GeSe 4 is a ferromagnet with T C = 5.8(2) K and a saturation moment at 2.2 K and 5.5 T of 6.92(2) μB/Eu. 151 Eu Mössbauer spectroscopic measurements of Eu 2 GeSe 4 and Eu 2 Ge 2 Se 5 at 78 K show isomer shifts of -12.43(4) mm/s and -12.69(5) mm/s, respectively, in accordance with divalent europium.

Bis(pentafluorophenyl) selenoxide and telluroxide were prepared by oxidation of the corresponding selenide and telluride with m-chloroperbenzoic acid. (C 6 F 5 ) 2 SeO crystallizes in the triclinic space group P1 with a = 9.9452(9), b = 14.871(2), c = 15.279(2) Å , a = 117.17(1), β = 101.02(1), γ = 95.39(1)°. The telluroxide (C 6 F 5 ) 2 TeO crystallizes as a dichloromethane or benzene solvate. The crystallographic data are for (C 6 F 5 ) 2 TeO · CH 2 Cl 2 : monoclinic space group P2 1 /n with a = 18.1918(2), b = 7.7545(1), c = 23.1719(3) Å , β = 97.9523(4)°; for (C 6 F 5 ) 2 TeO ÿ 1 / 2 C 6 H 6 : triclinic space group P1̄ with a = 5.7064(1), b = 10.9473(1), c = 12.1476(1) Å , a = 81.5366(8), γ = 86.8528(8), γ = 88.0700(5)°. The selenoxide forms hexamers, the telluroxide forms strong dimers with chalcogen-oxygen interactions.

Nitramide was investigated by multinuclear NMR spectroscopy, X-ray-diffraction and computational methods. The crystal structure analysis at various temperatures reveals a planar conformation of the molecule with a N-N bond length corresponding to a bond order between one and two. Hydrogen bonds connect the nitramide molecules side-on and end-on. This leads to the formation of layers in the crystal. Calculations were performed to explain the shorter N-N bond length in the crystal compared to the gas phase. The nitramide trimer is used as a model.

The structures of 1,2,4-triazolium chloride (C 2 H 4 N 3 )Cl and its derivative with antimony trichloride - (C 2 H 4 N 3 ) 2 [SbCl 5 ] · (C 2 H 4 N 3 )Cl containing unsubstituted 1,2,4-triazolium cations were determined. (C 2 H 4 N 3 )Cl crystallizes in the monoclinic system, space group P2 1 /n with the unit cell dimensions at 86 K: a = 9.425(2), b = 8.557(2), c = 11.158(2)Å , β = 95.87(3)°; V = 895.2(3)Å 3 , Z=8, dc = 1.566, d m = 1.56(2) g·cm -3 .At roomtemperature, crystals of (C 2 H 4 N 3 ) 2- [SbCl 5 ] · (C 2 H 4 N 3 )Cl are orthorhombic, space group P2 1 2 1 2 1 , a = 8.318(2), b = 11.381(2), c = 19.931(4) Å, V = 1886.8(7) Å 3 , Z = 4, d c = 1.917, d m = 1.91(2) g·cm -3 . In both crystals the 1,2,4-triazole rings are planar. The anionic sublattice of (C 2 H 4 N 3 ) 2 [SbCl 5 ]·(C 2 H 4 N 3 )Cl consists of polymeric [SbCl 5 ] n 2- zig-zag chains composed of distorted [SbCl 6 ] 3- octahedra connected via their vertices and the single Cl - anions. The cavities between the inorganic chains are filled by 1,2,4-triazolium cations. The nature of the distortion of the [SbCl 6 ] 3- polyhedra has been studied by examining correlations between the Sb-Cl bond lengths and the strength of hydrogen bonds, which join the anionic sublattice and the organic cations. This study confirms that the deformation of the [SbCl 6 ] 3- octahedra is caused by hydrogen bonds.

The compounds Ln 3 Cu 4 P 4 O 2-χ (Ln = Pr, Sm) were prepared by annealing the elemental components in a NaCl/KCl flux. They crystallize with an ordered Zr 3 Cu 4 Si 6 -type structure (space group I4/mmm, Z = 2), which was refined from single-crystal X-ray data for both compounds; Pr 3 Cu 4 P 4 O 2-χ : a = 397.8(1), c = 2658.7(3) pm, R = 0.046 for 235 structure factors and 19 variable parameters; Sm 3 Cu 4 P 4 O 2-χ : a = 392.8(1), c = 2643.6(3) pm, R = 0.057 for 145 F values and 19 variables. The refinements showed partial occupancy for the oxygen positions resulting in approximately 1.5 oxygen atoms per formula unit. Half of the phosphorus atoms form pairs with typical two-electron bond distances of 222.8(4) and 221.7(8) pm, respectively. Using oxidation numbers chemical bonding in these phosphide oxides can be rationalized with the formula (Ln +3 ) 3 (Cu +1 ) 4 (P-P) -4 (P -3 ) 2 (O -2 ) 1.5 . Hence, the empirical formula may also be doubled (Ln 6 Cu 8 P 8 O 3 ), and the compounds are expected to be semiconducting.

Powder-EPR-studies at T = 295, 130 and 13 K of the thiacrown ether Au II complex [Au II ([9]aneS 3 ) 2 ](BF 4 ) 2 diamagnetically diluted by the corresponding Zn II complex are reported. Due to the small anisotropy of the g and the 197 Au hyperfine tensor A Au , a large 197 Au quadrupole interaction and the noticeable linewidts, the powder spectra show a very complex pattern. Using S-band (2.4 GHz), X-band (9.5 GHz), Q-band (35 GHz) and W-band (94 GHz) frequencies the spectra could be analysed successfully. The spectra were simulated with a computer program which diagonalizes the spin-Hamiltonian matrix exactly. According to EHT-MO calculations most of the spin-density is located in an AuS 4 unit of the distorted AuS 6 unit.

An excellent supersilylation agent, supersilyl triflate, tBu 3 SiO 3 SCF 3 , is easily obtained from tBu 3 SiH and CF 3 SO 3 H. Supersilyl triflate, tBu 3 SiO 3 SCF 3 , reacts with lithium amide or lithium hydrazide to form the supersilyl amine, tBu 3 SiNH 2 , or the supersilyl hydrazines, tBu 3 SiNHNH 2 and tBu 3 SiNH-HNSitBu 3 , respectively. The structures of supersilyl triflate, tBu 3 SiO 3 SCF 3 , and bissupersilyl hydrazine, tBu 3 SiNH-HNSitBu 3 , have been determined by X-ray structure analysis.

[GaCl 2 (pyrazole) 4 ] + Cl - and [GaCl 2 (pyrazole) 4 ] + GaCl 4 - are formed in the reaction of pyrazole and anhydrous gallium trichloride in toluene/diethyl ether. The crystal structure of the chloride salt shows cations in a trans-conufiguration which are associated with the chloride counterions through N-H- -Cl hydrogen bonds.

The new manganese phosphate hydrate,Mn 6 (PO 4 ) 4· H 2 O, has been obtained as a single phase product using hydrothermal methods and the structure has been determined by single crystal X-ray diffraction. The title compound crystallizes in the monoclinic space group Cc with a = 934.18(10), b = 1743.68(18), c = 815.15(8) pm, β = 92.616(2)°, V = 1326.4(2)·10 6 pm 3 , Z = 4, and the refinement led to R1 = 0.0281 and Rw2 = 0.0728 (all data). The structure is composed of [PO 4 ] and [MnO x ] polyhedra (x = 6, 7) and might be described as a distorted primitive hexagonal packing of [PO 4 ] tetrahedra which are held together by Mn 2+ ions partially located in distorted trigonal prismatic positions. This leads to a dense three-dimensional framework structure. Magnetic susceptibility measurements verified the presence of high-spin Mn 2+ ions and thermogravimetric data confirm the chemical composition deduced from the single crystal structure determination.

11% Pt/C, 10% Pt + 1%Os/C, 9% Pt + 2%Os/C, 8% Pt + 3%Os/C, 7% Pt + 4%Os/C, 6% Pt + 5%Os/C and 5%Pt + 6% Os/C catalysts have been prepared for methanol oxidation reaction. Transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and cyclic voltammetry have been used to understand the nature of the species present in these catalysts. 7% Pt + 4% Os/C was the most active catalyst, while 8% Pt + 3% Os/C was the least active one. It is found that the metal particle size and distribution on the carbon support, the surface composition and the oxidation states of the metal particles, the metal-metal and metal support interactions are important parameters to define the activity of the catalyst.

The molecular structures of four silylbenzenes (benzenes with H 3 Si-substituents), viz. silylbenzene, 1,2-, 1,3- and 1,4-disilylbenzene, were studied by electron diffraction in the gas phase and by ab initio calculations. The structures of 1,2- and 1,4-disilylbenzene were also determined by X-ray diffraction experiments on single crystals grown in situ. The results are compared and discussed with the focus on the evaluation of the SARACEN method for the analysis of gas-phase data, and particularly on its ability to deal with small structural distortions. Important experimental structural parameters are the Si-C bond lengths [Å] and the ipso C-C-C angles [deg], which are 1.863(3) / 118.2(2) for gaseous silylbenzene (r α ), 1.875(2) / 119.9(2) for gaseous and 1.870(2) / 118.7(av) for solid 1,2-disilylbenzene, 1.871(1) / 119.4(3) for gaseous 1,3-disilylbenzene, 1.870(2) / 119.0(2) for gaseous and 1.866(3) / 117.4(2) for solid 1,4-disilylbenzene. The angle distortions in the benzene ring geometries are analysed and interpreted in terms of an additivity rule of the distortion caused by each of the silyl substituents. This additivity scheme predicts excellently the observed structures of the silylbenzenes and is in best agreement with the structures calculated ab initio. The slight distortion of molecular symmetry in the crystal structures makes a detailed comparison of the solid-state values impossible, but on average they are in good agreement with theory and predictions of the additivity model. The gas-phase values obtained by the SARACEN method show less pronounced distortions of the benzene ring geometries than observed or predicted by the other methods, but the trends of distortion are fully consistent.

2-Thiobarbituric acids 1 can be dimerized anodically in acceptable yields if the special ultrasonic electrolysis cell described here is used. In some cases two isomeric dimers 2 and 4 were isolated. 2 is of the same type as the corresponding barbituric acid dimers. The other dimer 4 has a completely different, tetracyclic structure characterized by NMR spectra and X-ray diffraction. The mechanism postulated for the formation of the tetracyclic dimers is supported by cyclovoltammetric measurements.

1 H, 13 C and 15 N NMR spectra of twenty substituted N-phenoxyethylanilines 1-20 were completely and unambiguously assigned using a combination of both homo- and heteronuclear (gs-COSY), 1 H detected heteronuclear one-bond (gs-HMQC) and long-range (gs- HMBC) gradient-selected correlation experiments. Correlations between chemical shifts and substituent constants are analyzed separately for both phenyl rings using variable substituents para to the fixed substituent -OCH 2 CH 2 NHC 6 H 5 (series I) and -NHCH 2 CH 2 OC 6 H 5 (series II), respectively. The correlation coefficient for chemical shifts vs. a linear combination of inductive and resonance substituent constants is high and improves when only the six values, corresponding to each para-monosubstituted series, were used. For nitrogen chemical shifts excellent linear dependences were obtained. The results show that the ethylene chain is not able to transmit the substituent effect from one aromatic ring to the other.

Two new triterpenes, adininaneone (1) and adininaonol (2) were isolated from Adiantum incisum. Three known triterpenes, adiantone (3), isoadiantone (4) and 23-hydroxyfernene (5) were also isolated for the first time from the methanolic extracts of A. insicum. The structures were elucidated with the help of modern spectroscopic techniques.

Fusanolides A (1) and B (2) were isolated from cultures of the fungus Fusarium sp. as pollen growth regulators and their structures were established by spectroscopic evidence. 1 completely inhibited pine pollen germination and tea pollen tube growth at a concentration of 300 mg/l, but 2 showed no inhibitory effect on them at the same concentration.

Treatment of O-benzyl protected S-glucosyl phosphorothioates with 1,3,5 trimethoxybenzene in the presence of iodine or boron trifluoride etherate led to appropriate aryl C-β-Dglucosides. The reaction of O-benzyl and O-acetyl-protected phosphorothioates of monosaccharides with allyltrimethylsilane, using boron trifluoride etherate as activator, gave mainly or exclusively, the corresponding 3-(α-D- glycopyranosyl)-1-propenes. C-Glucosidation of furan with O-benzyl protected S- glucosyl phosphorothioate in the presence of boron trifluoride etherate afforded (2- furyl)-α-C-glucoside.

1,3-Diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (2) is obtained from 2,3-dihydro-1,3- diisopropyl-4,5-dimethylimidazol-2-ylidene (1) and HBF 4 • Et 2 O; the X-ray structure of 2 is reported.

The reaction mixture of magnesium chloride with two equivalents of potassium anthranilate [K + Anth - ] in water gives on cooling to 0 °C a 60% yield of a precipitate which after drying in a vacuum has the composition [Mg(H 2 O) 6 ](Anth) 2 (1). Recrystallization from hot water affords an octahydrate identified as [Mg(H 2 O) 6 ](Anth) 2 (H 2 O) 2 (2) in a single crystal X-ray diffraction study. Contrary to findings for the related calcium, strontium and barium compounds, in the magnesium compound the anthranilate anions are not part of the coordination sphere of the metal atom. Thermal degradation of 1 or 2 at 125 °C gives the anhydrous product [Mg(Anth) 2 ], 3. Alternative preparative routes employed in previous studies gave only anhydrous material. The result of the present investigation confirms the outstanding stability of the hexa(aquo) complex of magnesium, as compared to the hydrates of the larger alkaline earth metals, in the presence of potential bioligands.

Chloride abstraction, using AgPF 6 , from tri(1- cyclohepta-2,4,6-trienyl)phosphane platinum and palladium dichloride, [P]MCl 2 [M = Pt (1), Pd (2)], affords the complexes {[P]MCl}PF 6 [M = Pt (3), Pd (4)] in good yields. The central metal is coordinated by the chloro ligand, the phosphorus atom and by three η 2 -C=C units, one of each C 7 H 7 ring. This assignment of a highly symmetrical C 3v structure is based on a consistent set of NMR data ( 1 H, 13 C, 31 P, 195 Pt NMR), in agreement with NMR data of the corresponding known neutral iridium and rhodium complexes [P]MCl [M = Ir (5), Rh (6)]. The chemical shift δ 103 Rh of 6 was determined, and a nearly linear relationship δ 195 Pt / δ 103 Rh was established.