Volume 71, Issue 12

The sulfido cobaltate(II) Na 3 CoS 3 was synthesized from stoichiometric quantities of Na 2 S, elemental cobalt and sulfur at a maximum temperature of 1100°C. According to Na 3 CoS 3 =Na 12 [Co 2 S 5 (S 2 )][Co 2 S 3 (S 2 )] the orthorhombic structure of a new type (space group Cmc 2 1 , a =884.24(2), b =2177.38(5), c =1193.20(3) pm, Z =12, R 1=0.0205) contains two different anions: i. dimers [Co 2 S 5 (S 2 )] 8− of two edge-sharing [CoS 4 ] tetrahedra with five sulfido and one η 1 -disulfido ligand; ii. chains ∞1[Co2S3(S2)]4−$_\infty ^1{[{\rm{C}}{{\rm{o}}_2}{{\rm{S}}_3}({{\rm{S}}_2})]^{4 - }}$ of [CoS 4 ] tetrahedra connected via μ -sulfido (3×) besides μ -1,2-disulfido (1×) ligands. The second title compound, Na 5 [CoS 2 ] 2 (Br), which has been likewise synthesized as a pure phase from stoichiometric quantities of Na 2 S, Co, S and NaBr, is isotypic to Na 5 [CoS 2 ] 2 (S) (Na 6 PbO 5 type; tetragonal, space group I 4 mm , a =914.58(7), c =625.59(5) pm; R 1=0.0412). The structure contains linear chains ∞1[CoS4/2]2−$_\infty ^1{[{\rm{Co}}{{\rm{S}}_{4/2}}]^{2 - }}$ running along the tetragonal c axis. In between, Br − ions are interspersed, which are coordinated by square pyramids of Na + ions. The isotypic hydrogensulfide Na 5 [CoS 2 ] 2 (SH) was obtained via the addition of NaSH. Several synthetic and structural arguments suggest that Na 5 [CoS 2 ] 2 (SH) and the previously described pure sulfide are the same compound. The results of DFT band structure calculations (GGA+ U , AFM spin ordering) are used to discuss and compare the chemical bonding in the new sulfido cobaltates(II) with that of the reference compound Na 2 [CoS 2 ]. They also allow for obtaining insight into the superexchange path, which is responsible for the strong antiferromagnetic Co spin ordering along the chains.

Chemical investigation of terrestrial and marine streptomycete isolates led to the identification of two new natural pigments, namely, 6-hydroxyisatin ( 3 ) and 6-hydroxy-5-methoxyisatin ( 4 ). Additionally, the strains delivered numerous known compounds, among them N β -acetyltryptamine, N -acetyltyramine, phenylacetamide, N -(2-phenethyl)acetamide, 1-acetyl- β -carboline, tyrosol, 2′-deoxyadenosine, 2′-deoxythymidine, anthranilic acid, 2′-deoxyuridine, indolyl-3-acetic acid, indolyl-3-carboxylic acid, and p -hydroxybenzoic acid. The isatin structures were deduced by NMR and mass studies and further confirmed by synthesis and by X-ray diffraction of the isomeric 5-hydroxy-6-methoxyisatin ( 5 ).

On the basis of 1,2-bis(5-tetrazolo)ethane (BTE) the corresponding twofold vinyl and allyl N- substituted derivatives were synthesized using 1,2-dibromoethane and allyl bromide, respectively. The compounds were obtained as two different constitutional isomers. Both species were analyzed using NMR and IR spectroscopy, elemental analysis, as well as mass spectrometry. In the case of the diallyl bistetrazoles, the two isomers were characterized using 2D NMR spectroscopy. The synthesis of the divinyl compounds gave crystals of the 2,2′- N -substituted isomer, which were analyzed by single-crystal X-ray diffraction. The thermal stability of the compounds was determined using differential scanning calorimetry (DSC) and gave decomposition temperatures around 190°C and 230°C. For the investigation of the inherent energetic potential, sensitivities toward physical stimuli and detonation parameters were determined. The compounds turned out to be insensitive toward friction and impact and possess moderate energetic properties.

9-Hydroxy-10,11-dehydro-sarcotrocheliol ( 1 ), a new pyrane-based cembranoid diterpene, has been isolated along with three other known compounds, namely, sarcotrocheliol acetate ( 2 ), (+)-sarcophytol A ( 3 ), and (−)-sarcophytonin A ( 4 ), from the organic extract of the soft coral Sarcophyton trocheliophorum . The chemical structures of compounds 1–4 were determined on the basis of their 1D and 2D NMR [ 1 H, 13 C, 1 H– 1 H correlation spectroscopy, heteronuclear multiple-quantum coherence, heteronuclear multiple-bond correlation, and nuclear Overhauser effect (NOE)] and mass spectra [electron ionization (EI), electrospray ionization, and high resolution mass spectrometry (HRMS)], and by comparison with related structures. The compounds 1–4 showed neither antimicrobial activity against 11 diverse tested microorganisms, nor cytotoxicity against brine shrimp, whereas the soft coral extract showed low cytotoxicity with a mortality rate of 1.7%.

When 4,4a-dihydro-3,3-dimethyl-1-phenyl-4,4-bis(trimethylsilyl)- 3H -2-oxa-3-sila-naphthaline (silaoxine C 22 H 34 OSi 3 ( 3 ); orthorhombic, space group Pna 2 1 , Z =4) was thermolized in a CO 2 atmosphere, the corresponding oxasilacyclobutane (silaoxetane) 5 was quantitatively formed. The [2+2] cycloreversion of the silaoxetane 5 occurred at temperatures higher than 120°C to give exclusively Ph 2 C=C(SiMe 3 ) 2 and (Me 2 SiO) n . Single crystals of Ph 2 C=C(SiMe 3 ) 2 ( 6 ; monoclinic, space group C 2/ c , Z =8) were isolated from this reaction. When the azasilacyclobutane (silaazetidine) C 25 H 43 NSi 4 ( 4 ; monoclinic, space group P 2 1 / n , Z =4) was reacted with an excess of CO 2 at 100°C an unknown intermediate was formed along with the benzophenonimine Ph 2 C=N(SiMe 3 ). The NMR resonances of this intermediate indicates the formation of the β -silalactone (silaoxetanone) C 10 H 24 O 2 Si 3 ( 7 ). At temperatures higher than 120°C the silaoxetanone 7 decomposed to give (Me 3 Si) 2 C=C=O and (Me 2 SiO) n , respectively.

BaSr 2 Ge 3 O 9 was prepared by high-temperature solid-state synthesis at 1100°C in a platinum crucible from barium carbonate, strontium carbonate, and germanium(IV) oxide. The compound crystallizes in the triclinic space group P 1̅ (no. 2) isotypically to walstromite BaCa 2 Si 3 O 9 . The structure was refined from single-crystal X-ray diffraction data: a =7.104(5), b =10.060(7), c =7.099(5) Å, α =83.0(2), β =77.0(2), γ =70.2(2)°, V =464.3(6) Å 3 , R 1=0.0230, and wR 2=0.0602 for all data. BaSr 2 Ge 3 O 9 is characterized by three-membered rings of germanate tetrahedra. There are three crystallographically different Ge sites (Ge1, Ge2, and Ge3) in each [Ge 3 O 9 ] 6− ring. The rings occur in layers with the apices of alternating rings pointing in opposite directions. The Sr 2+ and Ba 2+ ions are located in between. The Sr1 cation is eight-fold coordinated, while Sr2 is octahedrally surrounded by oxide anions, and the Ba cation again eight-fold coordinated.

A new centrosymmetric modification of the lead borate (Pb 4 O)Pb 2 B 6 O 14 has been obtained as a side phase through a facile hydrothermal reaction from Pb(BO 2 ) 2 ·H 2 O, H 2 O, and KOH as starting materials. The compound (Pb 4 O)Pb 2 B 6 O 14 -II crystallizes in the space group P 1̅ (no. 2) with the lattice parameters a =695.9(3), b =778.0(3), c =1408.3(3) pm, α =97.35(1)°, β =100.39(1)°, and γ =103.02(1)°. The structure consists of anti-parallel arranged B 6 O 14 chains and isolated oxygen-centered OPb 4 tetrahedra. The compound Pb 6 B 12 O 21 (OH) 6 constitutes the major phase of the synthesis, as verified through a Rietveld analysis. The characterization of (Pb 4 O)Pb 2 B 6 O 14 -II is based on a Rietveld analysis, single-crystal X-ray diffraction data, and FT-IR spectroscopy.

The quaternary gold arsenide oxides Ce 9 Au 5− x As 8 O 6 and Pr 9 Au 5− x As 8 O 6 were synthesized from the rare earth elements ( RE ), rare earth oxides, arsenic and gold powder at maximum annealing temperatures of 1173 K. The structures were refined from single crystal X-ray diffractometer data: Pnnm , a =1321.64(6) pm, b =4073.0(3), c =423.96(2), wR 2=0.0842, 3106 F 2 values, 160 variables for Ce 9 Au 4.91(4) As 8 O 6 and Pnnm , a =1315.01(4), b =4052.87(8), c =420.68(1) pm, wR 2=0.0865, 5313 F 2 values, 160 variables for Pr 9 Au 4.75(1) As 8 O 6 . They represent a new structure type and show a further extension of pnictide oxide crystal chemistry. A complex polyanionic gold arsenide network [Au 5 As 8 ] 15− (with some disorder in the gold substructure) is charge compensated with polycationic strands of condensed edge-sharing O@ RE 4/4 and O@ RE 4/3 tetrahedra ([ RE 4 O 3 ] 2 12+ ) as well as RE 3+ cations in cavities.

The structural and conformational properties of 2,2,2-trichloroethylacetate, H 3 CCO 2 CH 2 CCl 3 , have been determined in the gas phase using gas electron diffraction (GED). The experimental measurements were complemented by MP2 and DFT quantum-chemical calculations. Two conformers separated by a shallow rotational barrier have been identified, one of C 1 ( syn - gauche ) and the other of C s symmetry ( syn - anti ). All calculations indicate that syn - gauche is preferred in terms of enthalpy, whereas syn-anti seems to be slightly more stable regarding Gibbs free energy. In the gas-phase structure determination, dynamic models based on different potential energy surface scans were used. The one from dispersion-corrected density functional theory, predicting a preference of syn - gauche by 1.7kJmol −1 , was found to describe the experimental data best. One- and two-conformer models had to be rejected due to correlations and unrealistically large amplitudes. Experimentally determined structural parameters are in good agreement with both, quantum-chemical calculations as well as GED data for related compounds. Interacting quantum atoms (IQA) analyses revealed that interplay between the carbonyl group and the hydrogen as well as chlorine atoms of the trichloroethyl group accounts for most of the stabilisation of the C 1 conformer. With intramolecular symmetry-adapted perturbation theory (I-SAPT) analyses it was possible to further elucidate the nature of dominant interactions in the two conformers. Herein, preference of syn - gauche can for the most part be attributed to electrostatic and to some extent to induction and dispersion interplays. In contrast this conformer is severely destabilised through steric repulsion. These results were supported by NBO analyses.

Three series of rare earth-transition metal-indides RE 3 T 2 In 4 ( RE =Y, Gd–Tm, Lu; T =Ni, Ru, Rh) were synthesized from arc-melted RE 3 T 2 precursor compounds and indium tear shot in sealed niobium ampoules using different annealing sequences. The new indides crystallize with the hexagonal Lu 3 Co 2 In 4 -type structure, space group P 6̅. All samples were characterized on the basis of Guinier powder patterns and six structures were refined from single crystal X-ray diffractometer data. The RE 3 T 2 In 4 structures are derived from the ZrNiAl type through RE /In ordering, paralleled by a symmetry reduction from P 6̅2 m to P 6̅. This induces twinning for some of the investigated crystals. The main crystal chemical motifs of the RE 3 T 2 In 4 structures are trigonal prisms of rare earth, respectively indium atoms that are filled by the transition metals.

Zn(II) halide complexes of the form L 2 ZnX 2 (X=Cl, Br, I) containing bio-relevant or bio-related ligands like 1-alkyl-imidazoles (alkyl=methyl, ethyl and iso-propyl) or (–)-nicotine are presented. All complexes were characterized by 1 H NMR spectroscopy, mass spectrometry and elemental analysis. The molecular structures of the majority of complexes were determined by single crystal X-ray diffraction. The zinc ion exists in a tetrahedral environment coordinated by two halide anions and two nitrogen atoms of the N-heterocycles. Upon photoexcitation the nicotine complexes feature a blue emission which we tentatively assign to phosphorescence.

Single crystals of compounds with the composition Ln 2 O[SeO 3 ] 2 ( Ln =Sm–Tm) were synthesized by solid-state reactions of the lanthanoid sesquioxides ( Ln 2 O 3 ) with the corresponding tribromides ( Ln Br 3 ) and selenium dioxide (SeO 2 ) in a molar ratio of 2:1:2 in evacuated torch-sealed silica ampoules. For the terbium case, Tb 4 O 7 and SeO 2 have been reacted with elemental Tb in a molar ratio of 3:14:2. These lanthanoid(III) oxide oxoselenates(IV) all crystallize tetragonally with the space group P 4 2 / ncm and decreasing lattice parameters from the lighter to the heavier Ln 3+ cations (from a =1077.03(8) pm and c =526.38(4) pm for Ln =Sm to a =1049.60(8) pm and c =516.04(4) pm for Ln =Tm) according to the lanthanide contraction. They show a three-dimensional network of condensed [ Ln O 8 ] 13− polyhedra with a channel structure, where all ψ 1 -tetrahedral [SeO 3 ] 2− units are coordinating with their O 2− anions to square antiprisms [ Ln O 8 ] 13− and pointing with their non-bonding electron pairs into the empty channels, which propagate along [001]. As another characteristic feature of the crystal structure, [O Ln 4 ] 10+ tetrahedra containing the non- selenium-bonded O 2− anions are trans -edge-connected to form {[OLn4/2e]4+}∞1${}_\infty ^{\rm{1}}{\rm{\{ [O}}Ln_{4/2}^{\rm{e}}{{\rm{]}}^{{\rm{4}} + }}{\rm{\} }}$ chains, which run parallel to the lone-pair channels in [001] direction and build up a tetragonal rod-packing.

Aiming at the development of new photolabeling agents, the synthesis and photoreactivity of all monofluorinated derivatives of 2-azido-1-methylbenzimidazole are described. In the case of 4-, 5-, or 7-fluorination, irradiation in the presence of carboxylic acids (300 nm, Rayonet) afforded the monofluorinated 2-amino-6-acyloxybenzimidazoles in a regioselective manner, presumably after conversion of the initially formed nitrene to the N -cyanodiazaxylylene. Incorporation of chloride was also possible, and yields were comparable to those observed for the non-fluorinated parent compound. When blocking the reactive 6-position by a fluoro substituent, the title reaction was not possible. The analysis of the 19 F NMR chemical shifts of the 5- and 7-monofluorinated products allowed the distinction between carboxylates and other nucleophiles.