Volume 61, Issue 1

Complexes [Me 2 Au(PMe 3 ) 2 ] + X − with X = I and ClO 4 have been prepared by several conventional routes in good yields. The products are thermally stable and decompose above 130 °C with reductive elimination of ethane. The two salts crystallize as isomorphous orthorhombic dichloromethane solvates. The cations have the cis-configuration based on a crystallographically imposed C 2v symmetry. Owing to the trans influence of the tertiary phosphine ligands the Au-C bonds are significantly shorter than in standard reference cases. The cations are stacked in pairs of columns running parallel to the c axis of the unit cell with the Me 2 Au units oriented in opposite directions and slightly interlocked. The anions are inserted into the pockets formed by the four Me 3 P groups of each pair of neighbouring cations in the same column. The large channels between the double columns are filled by the solvent molecules, which could be localized for the perchlorate salt, but were disordered and deficient in the iodide case.

Bis(p-tolylsulfonylmethylisocyanide)silver nitrate is obtained from the reaction of the isocyanide ligand with silver nitrate in chloroform regardless of the applied ratio of the reactands (1:1 or 2:1). The crystal structure of the product has been determined. In the complex molecule with C 2 symmetry, the nitrate anion is attached to the silver center as an η 2 -chelating ligand. Owing to this approach of the NO 3 ligand, the RNC-Ag-CNR axis (R = 4-Me-C 6 H 4 -SO 2 -CH 2 ) is bent [from 180 to 162.1(2)°], but the geometry of the nitrate is not significantly distorted, suggesting only weak coordinative bonding. The structure is thus intermediate between that of a molecular complex with a tetrahedral coordination and that of an ionic compound with linear coordination of the silver center.

The lanthanide oxide nitrates LnONO 3 with Ln = Pr, Nd, and Sm-Yb were synthesised by thermal decomposition of hydrated lanthanide nitrates. The compounds were refined isotypically to YONO 3 in the tetragonal space group P4/nmm and the structure is closely related to the PbFCl-type. Because of the orientational disorder of NO 3 − in this structure refinement a possible superstructure is discussed. Together with the oxide ions, the metal ions form [Ln 2 O 2 ] 2+ layers, alternating with double (NO 3 )− layers. Lattice parameters were determined by powder X-ray diffraction, and the structure of HoONO 3 was refined by Rietveld analysis. Some thermoanalytical data are given and magnetic properties were measured for LnONO 3 with Ln = Nd, Sm, Eu, and Gd.

The new compounds Pr 3 Pd 6 Sb 5 (a = 13.442(3), b = 4.442(1), c = 9.994(2) Å ), Nd 3 Pd 6 Sb 5 (a = 13.412(3), b = 4.431(1), c = 9.962(2) Å), and Gd 3 Pd 6 Sb 5 (a = 13.293(2), b = 4.397(1), c = 9.881(2) Å) are isotypic and crystallize with the Ce 3 Pd 6 Sb 5 type structure (Pmmn; Z = 2). The rare-earth metal atoms are arranged in form of three pseudo-body-centered subcells, whereas Pd and Sb atoms form a three-dimensional arrangement derived from the well-known ThCr 2 Si 2 and CaBe 2 Ge 2 structures. GdPdSb (a = 4.566(1), c = 7.444(1) Å) and DyPdSb (a = 4.545(1), c = 7.354(1) Å) crystallize with an ordered variant of the CaIn2 type structure (P6 3 mc; Z = 2), also called as LiGaGe type, with slightly puckered hexagon nets of Pd and Sb atoms, which trigonally coordinate each other. In this series a decreasing radius of the rare-earth metal allows a tetrahedral non-metal environment of the Pd atoms and accordingly ScPdSb (a = 6.310(1) Å) forms the MgAgAs type structure (F4̄3m; Z = 4), a filled variant of the sphalerite type. The antimonides were prepared by heating mixtures of the elements at 600 °C and subsequent annealing at 900 - 1100 °C. Their structures have been determined by single-crystal X-ray methods.

The rare earth-cobalt-indides RE 14 Co 3 In 3 (RE = Y, Tb, Dy, Ho, Er) were prepared in polycrystalline form from the elements by arc-melting. Small single crystals were grown through a special annealing sequence. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14 Co 2 In 3 (Gd 14 Co 3 In 2.7 ) type, P4 2 /nmc, Z = 4, a = 959.0(1), c = 2319.1(5) pm, wR2 = 0.055, 2289 F 2 values, 65 variables for Y 13.90 Co 2.99 In 3.02 , a = 953.8(1), c = 2315.8(5) pm, wR2 = 0.108, 2357 F 2 values, 65 variables for Tb 13.92 Co 3.01 In 2.92 , a = 949.24(3), c=2296.5(1) pm, wR2= 0.129, 2518 F 2 values, 65 variables for Dy 13.90 Co 2.97 In 2.95 , a=946.3(1), c = 2289.0(5) pm, wR2 = 0.099, 2297 F 2 values, 64 variables for Ho 14 Co 2.80 In 2.89 , and a = 941.0(1), c = 2274.2(5) pm, wR2 = 0.140, 2450 F 2 values, 65 variables for Er 13.83 Co 2.88 In 3.10 . All RE 14 Co 3 In 3 indides show a small degree of In/Co mixing (between 7 and 16% Co) on the 4c In1 site and defects on the 8g Co1 positions (between 84 and 95% Co). Except for the holmium compound, the RE 14 Co 3 In 3 intermetallics also reveal RE/In mixing on the 4c RE1 sites, leading to the refined compositions. The seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE 14 Co 3 In 3 structures consist of a complex intergrowth of rare earth based polyhedra. Both cobalt sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell with an In2-In2 distance of 300 pm (for Ho 14 Co 2.80 In 2.89 ). The crystal chemistry of the RE 14 Co 3 In 3 indides is discussed.

The reaction of the 1,2-dihalodiborane(4) B 2 (NMe 2 ) 2 Cl 2 with the lithium tungsten salts Li[(η 5 - C 5 H 5 )(R 3 P)(OC) 2 W] [R = Me (3a), Ph (3b)] yields via alkali salt elimination the phosphinesubstituted diborane(4)yl tungsten complexes [(η 5 -C 5 H 5 )(R 3 P)(OC) 2 W-{B(NMe 2 )-B(NMe 2 )Cl}] [R = Me (4a), Ph (4b)]. Both compounds have been fully characterized in solution by NMR and IR spectroscopy and 4a additionally by X-ray diffraction analysis.

The so far unknown lead tricyanomethanide, Pb[C(CN) 3 ] 2 , was obtained from a saturated aqueous solution of PbCl 2 and solid AgC(CN) 3 . Its IR spectrum and thermal behaviour are described. The crystal structure was determined by single-crystal X-ray diffraction (trigonal, P31m, Z = 3, a = 1414.4(5), c = 409.02(6) pm, R 1 = 0.0249, wR 2 = 0.0527). Two crystallographically independent ninefold coordinated Pb atoms are connected by planar tricyanomethanide ions in two distinct bridging coordination modes. The Pb−N distances range between 254 and 293 pm.

The reactions of methyl(2-pyridyl)ketone oxime, (py)C(Me)NOH, with zinc chloride have been investigated. An excess of the ligand in EtOH/MeCN affords the mononuclear complex [ZnCl 2 {(py)C(Me)NOH} 2 ] (1) in moderate yield. The metal ion is coordinated by two chloro ligands and two N,N′- chelating (py)C(Me)NOH molecules. The six-coordinate molecule is the ciscis- trans isomer considering the positions of the coordinated chlorine, pyridyl and oxime nitrogen atoms, respectively. The reaction between equimolar quantities of ZnCl 2 , (py)C(Me)NOH and LiOH·H 2 O in EtOH/MeCN leads to the tetranuclear cluster [Zn 4 (OH) 2 Cl 2 {(py)C(Me)NO} 4 ] (2) in high yield. The molecule lies on a crystallographic inversion center and has an inverse 12-metallacrown- 4 topology. Two triply bridging hydroxides are accommodated within the metallacrown ring. Each (py)C(Me)NO− ligand adopts the 2.111 coordination mode (Harris notation), chelating one ZnII ion and bridging a Zn II 2 pair. Two metal ions are in a distorted O 2 N 4 octahedral environment, whereas the other two are in a severely distorted tetrahedral O 3 Cl environment. Complex 2 joins a small family of structurally characterized zinc(II) metallacrown complexes. The IR data are discussed in terms of the nature of bonding and the structures of the two complexes.

A simple, convenient, and efficient one-pot protocol for the reductive cleavage of disulfides and Michael addition to α,β -unsaturated carbonyl compounds mediated by the Zn/AlCl 3 system in aqueous media is reported.

A series of some new 3,5-unsymmetrically substituted 1,4-dihydropyridines have been synthesized, which have ethoxycarbonyl and acetyl groups on 3- and 5-positions, respectively. A three-step procedure has been examined to increase the yield of the desired products, by suppressing the formation of the symmetrically substituted 3,5-diacetyl-1,4-dihydropyridines and 3,5-diethoxycarbonyl- 1,4-dihydropyridines.

A new flavone sulfonic acid 1 named niruriflavone was isolated from the 70% ethanolic extract of the whole plant of Phyllanthus niruri (Euphorbiaceae), together with 6,10,14-trimethyl-2- pentadecanone, hypophyllanthin, gallic acid, brevifolin carboxylic acid, methyl brevifolin carboxylate, isoquercetin, quercetin-3-O-β -D-glucopyranosyl(1→ 4)-α-rhamnopyranoside, corilagin, and isocorilagin, whose structures were determined by spectroscopic methods and comparison with published data. In an ABTS cation radical reduction assay, niruriflavone (1) exhibited potent radical scavenging properties. A biological test system based on bioluminescence of the dinoflagellate Lingulodinium polyedrum did not reveal any prooxidant properties of 1 at 50 μM.

The synthesis and structure of (C 4 H 3 S)TeCH 2 CH 2 OC 6 H 5 (1) (C 4 H 3 S = thiophen-2-yl) are reported and compared to those of the analogous selenium compound (C 4 H 3 S)SeCH 2 CH 2 OC 6 H 5 previously synthesized by our group. The compound was characterized by 1 H, 13 C{ 1 H}-, and 125 Te- NMR spectroscopy as well as by X-ray single crystal crystallography. 1 crystallizes in the monoclinic crystal system, space group P2 1 , with Z = 2, and unit cell dimensions a = 10.618(2) Å , b = 5.357(1) Å , c = 10.684(2) Å , β = 96.57(3)°. The lattice is composed of discrete molecules that are joined together by weak hydrogen bonds into a three-dimensional network. The thiophen-2-yl ring is disordered and shows two alternative orientations with the site occupation factors of 0.70(1) and 0.30(1). All bond parameters are quite normal. The comparison of the lattices in 1 and in its selenium anologue shows that while the closest intermolecular contacts are similar, the packing of the molecules is different.

Methyl 3-aminothiophene-2-carboxylate reacts readily, in the presence of triethylamine, with hydrazonoyl chlorides (7a - c) to afford good yields of the corresponding N-arylamidrazones (8a - c). The latter acyclic adducts undergo, in the presence of t-BuOK/t-BuOH, cyclocondensation accompanied by elimination of the acetyl group present in 8, to deliver the respective thieno-1,3,4-triazepin- 5-ones 10a - c.

The crystal structures of piperazinium tetrahalogenometallates (II) [C 4 H 12 N 2 ]MX 4 (M = Zn, Hg; X = Br, I), orthorhombic with space group P2 1 2 1 2 1 and Z = 4 are isostructural with [C 4 H 12 N 2 ]CdI 4 . The structure consists of piperazinium cations and isolated tetrahedralMX4 anions. [C 4 H 12 N 2 ]ZnBr 4 (1): a = 850.4(2), b = 1146.5(3), and c = 1228.4(4) pm at 300(2) K, [C 4 H 12 N 2 ]ZnI 4 (2): a = 886.89(6), b = 1209.11(9), and c = 1293.79(9) pm at 223(2) K, [C 4 H 12 N 2 ]HgBr 4 (3): a = 865.48(14), b = 1158.7(3), and c = 1233.3(2) pm at 293(2) K, [C 4 H 12 N 2 ]HgI 4 (4): a = 899.6(2), b = 1230.0(2), and c = 1299.5(3) pm at 293(2) K. All crystals show a structural phase transition at about 560 K and decomposition temperatures above 600 K. The lattice stability of the crystals is well explained by N-H · · · X hydrogen bond networks.

In boiling pyridine, lapachol (1) is transformed into novel asymmetric naphthoquinone derivative, quadrilone (2), and into dehydro-α-lapachone (3), and adenophyllone (4). Lapachol used in the present study was isolated from the heartwood of Heterophragma quadriloculare and found to be the most abundant naphthoquinone.

From the leaves of Tithonia diversifolia, four compounds were isolated and identified. Two of them, the anthraquinone tithoniquinone A (1) with an unusual substitution pattern on the anthraquinone skeleton, and the ceramide, named tithoniamide B (2a), are reported for the first time as natural products. Their structures were determined by comprehensive analyses of their 1D and 2D NMR and electron impact (EI) mass spectral data. The remaining two known compounds were identified as psoralen and l-quebrachitol. Preliminary studies showed that tithoniaquinone A (1) is strongly antibacterial and antifungal against Gram-positive Bacillus megaterium and Microbotryum violaceum, respectively, while psoralen has strong algicidal, fungicidal, and antibacterial activities.

6-Thioxo-1,2,5-oxadiazinan-3-ones 5, easily available by cyclic thiocarbonylation of N α ,Ndisubstituted α-aminocarbohydroxamic acids 4 with 1,1′-thiocarbonyldiimidazole, are transformed by hydrazine or hydroxylamine into 3-amino-2-thiohydantoins 6 and 3-hydroxy-2-thiohydantoins 7.

From the leaves of Zizyphus glabrata, a new dammarane-type triterpene, pseudojujubogenin -3-O- β -D-glucopyranoside, along with the known ceanothane triterpenes, granulosic acid, ceanothic acid and daucosterol were isolated. The structures of the compounds were fully characterized by detailed NMR investigations including 1 H and 13 C NMR, HSQC, COSY, HMBC and NOESY experiments. In addition, the dammarane glycoside was tested for its potential to inhibit various bacteria and was found to possess significant bactericidal activity. The 1 H, 13 C and full 2D-NMR data on granulosic acid has also been presented. This is the first report on the chemical constituents of the leaves of Z. glabrata.

The (Z)-2-arylidene-quinuclidines 5 - 8 were synthesized. Their reaction with aliphatic dibasic functional reagents in both basic and acidic conditions afforded the fused heterocycles 9, 10 and 11. However, the reaction of arylidene derivative 5 with an aromatic dibasic functional reagent gave benzimidazole 13 in lieu of the anticipated tetracyclic system, quinuclidino[3,2-e]benzo[b]-1,4-diazepine 12. Cycloadditions of 5 with different reagents gave the heterocyclic derivatives 17, 19, 22 and 23. Acid-catalyzed cyclization of 5 with excess resorcinol gave 24. Compounds 9a, 19 and 24 showed antibacterial activities.

A series of N-, S-, and O-mononitro- and dinitrobenzyl derivatives of heterocycles was synthesized by alkylation of heterocyclic bases with the respective nitrobenzyl chlorides. Of the newly synthesized compounds, dinitrobenzylsulfanyl derivatives of 1-methyl-2-mercaptoimidazole (2c) and of 5-nitro- and 5,6-dichloro-2-mercaptobenzimidazole (8b and 8c, and 8e and 8f, respectively) showed considerable antimycobacterial activity. On a molar basis, nine of the novel compounds showed also a considerably higher antiprotozoal efficacy than metronidazole that reduced T. hominis viability to 73.5% at 8 μg/ml.

Well-shaped single crystals of binary AuSn 2 were obtained as a side product during the synthesis of LiAu 3 Sn 4 . The structure of AuSn 2 has been studied by X-ray diffractometer data: Pbca, Z = 8, a = 689.8(1), b = 701.1(1), c = 1177.3(2) pm, wR2 = 0.0533, 1234 F 2 values, and 29 variables. The gold atoms show a distorted octahedral coordination by tin at Au-Sn distances ranging from 272 to 283 pm. The structure can be considered as an intergrowth of pyrite and marcasite related slabs. Consequently one observes Sn1-Sn2 dumb-bells with a Sn-Sn distance of 289 pm, while all other Sn-Sn distances are larger than 322 pm.

The title compound C 18 H 30 O 3 represents an optically pure member of a class of ‘pseudosteroids’, i. e. perhydrostilbene derivatives which mimic steroidal androgens (in the way like hexestrols or stilbestrols serve to substitute natural estrogens). The molecule 2 is characterized by three consecutive chiral centers leading to eight possible stereoisomers including four diastereomers. All enantiomers have been separated and their biological profile has been determined. As the result of the crystal structure presented here the two symmetry independent molecules display the configuration R,R,R at the centers of chirality.

A new eudesmane glucoside has been isolated from the aerial part of Apodytes dimidiata, an Icacinaceous plant widely used in the Southern African countries for its molluscicidal activities. The structure of the new compound was determined by spectroscopic methods. The chemosystematics of the genus belonging to the family Icacinaceae is discussed.