(2‐Aminoethanethiolato‐N,S)bis(ethylenediamine‐N,N′)cobalt(III) dinitrate

In the title compound, [Co(C₂H₆NS)(C₂H₈N₂)₂](NO₃)₂, the Co^III atom has a slightly distorted octahedral geometry, coordinated by one 2‐amino­ethane­thiol­ate and two ethyl­enedi­amine ligands. The three five‐membered chelate rings adopt a gauche conformation with the unfavoured (lel)₂(ob) form, which is ascribed to hydrogen bonds between the amine groups in the complex cation and the nitrate counter‐anions [N?O 2.900 (3)–3.378 (3) Å].     

Separation of (3R, 3′ R)-, (3R, 3′ S; meso)-, (3S, 3′ S)- Zeaxanthin, (3R, 3′ R, 6′ R)-, (3R, 3′ S, 6′ S)- and (3S, 3′ S, 6′ S)-Lutein via the dicarbamates of (S)-(+)-α-(1-naphthyl) ethyl isocyanate

A method is described for the qualitative and quantitative determination of configurational isomers of zeaxanthin (=3,3′ -dihydroxy-β, β -carotene) and lutein (=3,3′ -dihydroxy-α -cartotene). It is based on the reaction of these zeaxathin and lutein isomers with (S)-(+)-α-(1-naphthyl) ethyl isocyanate to afford diastereomeric dicarbamates, which are analyzed by HPLC.     

Aquabromo(6‐carboxypyridine‐2‐carboxylato‐O,N,O′)mercury(II)

The title compound, [HgBr(C₇H₄NO₄)(H₂O)], was obtained by the reaction of an aqueous solution of mercury(II) bromide and pyridine‐2,6‐di­carboxylic acid (picolinic acid, dipicH₂). The shortest bond distances to Hg are Hg—Br 2.412 (1) Å and Hg—N 2.208 (5) Å; the corresponding N—Hg—Br angle of 169.6 (1)° corresponds to a slightly distorted linear coordination. There are also four longer Hg—O interactions, three from dipicH^? [2.425 (4) and 2.599 (4) Å within the asymmetric unit, and 2.837 (4) Å from a symmetry‐related mol­ecule] and one from the bonded water mol­ecule [2.634 (4) Å]. The effective coordination of Hg can thus be described as 2+4. The mol­ecules are connected to form double‐layer chains parallel to the y axis by strong O—H?O hydrogen bonds between carboxylic acid groups of neighbouring mol­ecules, and by weaker hydrogen bonds involving both H atoms of the water mol­ecule and the O atoms of the carboxylic acid groups.     

Total Syntheses of (±)‐Fawcettimine, (±)‐Fawcettidine, (±)‐Lycoflexine,and (±)‐Lycoposerramine‐Q

The total syntheses of four fawcettimine‐related Lycopodium alkaloids, (±)‐fawcettimine, (±)‐fawcettidine, (±)‐lycoposerramine‐Q, and (±)‐lycoflexine, were completed in a highly stereoselective manner. The Pauson–Khand reaction of 4‐methylidene‐6‐siloxyoct‐1‐en‐7‐yne followed by regio‐ and stereoselective hydrogenation led to the short‐step preparation of the bicyclo[4.3.0]nonenone intermediate bearing a methyl group with the required stereochemistry. The subsequent chemical manipulation of the bicyclic compound afforded the 6‐5‐9‐membered tricyclic dioxo compound, which was then transformed into the four targeted alkaloids in an alternative and more efficient fashion.     

Stereochemische Korrelationen zwischen (2R,4′R,8′R)-α-Tocopherol, (25S,26)-Dihydroxycholecalciferol, (–)-(1S,5R)-Frontalin und (–)-(R)-Linalol

Stereochemical Correlations between (2R,4′R,8′R)-α-Tocopherol, (25S,26)-Dihydroxycholecalciferol, (–)-(1S,5R)-Frontalin and (–)-(R)-Linalol The optically active C₅- and C₄-building units 1 and 2 with their hydroxy group at a asymmetric C-atom were transformed to (–)-(1S,5R)-Frontalin ( 7 ) and (–)-(3R)-Linalol ( 8 ) respectively; 1 and 2 had been used earlier in the preparation of the chroman part of (2R,4′R,8′R)-α-Tocopherol ( 6a , vitamin E), and for introduction of the side chain in (25S,26)-Dihydroxycholecalciferol ((25S)- 4 ), a natural metabolite of Vitamin D₃. The stereochemical correlations resulting from these converions fit into a coherent picture with those correlations already known from literature and they confirm our earlier stereochemical assignments. A stereochemical assignment concerning the C(25)-epimers of 25,26-Dihydroxycholecalciferol that was in contrast to our findings and that initiated the conversion of 1 and 2 to 7 resp. 8 for additional stereochemical correlations has been corrected in the meantime by the authors [26].     

1, 3, 4, 4'‐Tetra(triphenylphosphanimin)‐2‐iodo‐2‐butenal‐4‐carboniumiodid, [O=C(NPPh3)C(I)=C(NPPh3)‐C(NPPh3)2]+I‐

Pale yellow single crystals of [O=C(NPPh₃)C(I)=C(NPPh₃)‐C(NPPh₃)₂]⁺I^‐·1.5 thf ( 1 ·1.5 thf) have been obtained by the reaction of INPPh₃ with thallium in thf suspension. They are characterized by IR spectroscopy and by a crystal structure determination. 1 ·1.5 thf crystallizes in the monoclinic space group P2₁/n, Z = 4, lattice dimensions at ‐83?C: a = 1101.7(1), b = 3449.0(2), c = 2000.4(1) pm, β = 104.88(1)?, R₁ = 0.0382. 1 can be understood as a cationic variation of (Z)‐2‐butenale in which all H atoms are substituted by triphenylphosphoraneimine residues and by a iodine atom, respectively.     

mer‐Bis(1,4‐dibenzoylthiosemicarbazidato‐κ3O,N,O′)cobalt(II)

The title complex, [Co(C₁₅H₁₂N₃O₂S)₂], consists of an octahedrally coordinated Co^II ion, with two crystallographically independent 1,4‐dibenzoylthiosemicarbazidate ligands in a tridentate mer coordination [Co—O = 2.064 (3)–2.132 (3) Å and Co—N = 2.037 (3)–2.043 (3) Å]. There are intermolecular N—H...S hydrogen bonds involving one ligand and strong π–π stacking interactions involving the other ligand, resulting in a three‐dimensional supramolecular framework. The hydrogen bonds and π–π interactions, as well as different intramolecular aryl–benzamide H—C...H(—N) distances, give rise to a difference in conformation between the two ligands.     

(S,S)‐Lactoyllactic acid and (S,S,S)‐lactoyllactoyllactic acid

The dimeric condensation product of lactic acid, namely (S,S)‐2‐[(2‐hydroxypropanoyl)oxy]propanoic acid, C₆H₁₀O₅, (I), crystallizes with two independent molecules in the asymmetric unit, which both have an essentially planar backbone. The trimeric condensation product, namely (S,S,S)‐3‐hydroxybut‐3‐en‐2‐yl 2‐[(2‐hydroxypropanoyl)oxy]propanoate, C₉H₁₄O₇, (II), has one molecule in the asymmetric unit and consists of two essentially planar parts, with the central C—O bond in a gauche conformation. Both molecules of the dimer are involved in intermolecular hydrogen bonds, forming chains with a C(8) graph set. These chains are connected by D(2) hydrogen bonds to form a two‐dimensional layer. The trimer forms hydrogen‐bonded C(10) and C₂²(6) chains, which together result in a two‐dimensional motif. The Hooft method [Hooft, Straver & Spek (2008). J. Appl. Cryst. 41 , 96–103] was successfully applied to the determination of the absolute structure of (I).     

Bis(8‐quinolinolato‐N,O)platinum(II) and its synthetic intermediate, 8‐hydroxyquinolinium dichloro(8‐quinolinolato‐N,O)platinate(II) tetrahydrate

Bis(8‐quinolinolato‐N,O)­platinum(II), [Pt(C₉H₆NO)₂], (I), has a centrosymmetric planar structure with trans coordination. The molecules form an inclined π stack, with an interplanar spacing of 3.400 (6) Å. 8‐Hydroxy­quinolinium dichloro(8‐quinolinolato‐N,O)­platinate(II) tetrahydrate, (C₉H₈NO)[PtCl₂(C₉H₆NO)]·4H₂O, (II), is soluble in water and is regarded as the synthetic intermediate of the insoluble neutral compound (I). The uncoordinated 8‐hydroxy­quinolinium cations and the monoquinolinolate complexes form an alternating π stack. The origins of fluorescence and phosphorescence in (II) are assigned to the 8‐hydroxy­quinolinium cation and the monoquinolinolate–Pt complex, respectively.     

cis‐Di­aqua­bis(trans‐cinnamato‐O,O′)zinc(II)

The title complex, [Zn(C₉H₇O₂)₂(H₂O)₂], shows a distorted octahedral coordination and has a crystallographic twofold rotation axis. Intermolecular O—H?O hydrogen bonding forms a two‐dimensional network in the ab plane.     

Synthesis of well‐defined second‐generation dendritic polymers of isoprene (I) and styrene (S): (S2I)3, (SI′I)3, (I″I′I)3, and (I′2I)4

The synthesis of second‐generation (G‐2) dendritic polymers of isoprene (I) and styrene (S) was achieved with anionic polymerization high‐vacuum techniques and by performing the following steps: (1) selective reaction of a living chain with the chlorosilane group of 4‐(chlorodimethylsilyl)styrene (a dual‐functionality compound) to produce a macromonomer, (2) addition of a second living chain (same or different) to the double bond of the macromonomer, (3) polymerization of I with the anionic sites, and (4) reaction of the produced off‐center living species with trichloromethyl silane or tetrachlorosilane (CH₃SiCl₃ or SiCl₄). The combined characterization results showed that the G‐2 dendritic macromolecules synthesized—(S₂I)₃, (SI′I)₃, (I″I′I)₃, (I′₂I)₄—have a high molecular and compositional homogeneity. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1519–1526, 2002     

Layered (ethyl­ene­di­amine‐κ2N,N′)cobalt(II) molybdate(VI)

The structure of poly­[[(ethyl­enedi­amine‐κ²N,N′)­cobalt(II)]‐μ‐tetra­oxo­molyb­dato(VI)], [Co(C₂H₈N₂)MoO₄]_n or [CoMoO₄(C₂H₈N₂)]_n, is composed of puckered layers constructed from MoO₄ tetrahedra and CoN₂O₄ octahedra, with the ethyl­enedi­amine ligand coordinated to the Co atom in a cis fashion. Each pair of cobalt sites forms a binu­clear edge‐sharing unit through a {Co₂O₂} interaction. The binuclear octahedral units are interconnected through the bridging MoO₄ tetrahedra into a layer structure.     

Actinide–Pnictide (An−Pn) Bonds Spanning Non‐Metal,Metalloid, and Metal Combinations (An=U,Th; Pn=P,As, Sb,Bi)

The synthesis and characterisation is presented of the compounds [An(Tren^DMBS){Pn(SiMe₃)₂}] and [An(Tren^TIPS){Pn(SiMe₃)₂}] [Tren^DMBS=N(CH₂CH₂NSiMe₂Bu^t)₃, An=U, Pn=P, As, Sb, Bi; An=Th, Pn=P, As; Tren^TIPS=N(CH₂CH₂NSiPrⁱ₃)₃, An=U, Pn=P, As, Sb; An=Th, Pn=P, As, Sb]. The U?Sb and Th?Sb moieties are unprecedented examples of any kind of An?Sb molecular bond, and the U?Bi bond is the first two‐centre‐two‐electron (2c–2e) one. The Th?Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U?Bi complex is the heaviest 2c–2e pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An?An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U?Pn bonds degrade by homolytic bond cleavage, whereas the more redox‐robust thorium compounds engage in an acid–base/dehydrocoupling route.     

(2,2′‐Biquinoline‐κ2N,N′)bis(nitrato‐κ2O,O′)copper(II)

In the title monomer, [Cu(NO₃)₂(C₁₈H₁₂N₂)], the six‐coordinated Cu^II atom lies on a twofold axis which bisects one of the ligands (a chelating biquinoline) and duplicates the remaining ligand, a chelating nitrate. The latter binds in a very asymmetric way, consistent with a Jahn–Teller distortion in the coordination polyhedron which, due to the triple chelation, is extremely distorted and difficult to describe in terms of any regular model.     

Actinide–Pnictide (An−Pn) Bonds Spanning Non‐Metal,Metalloid, and Metal Combinations (An=U,Th; Pn=P,As, Sb,Bi)

The synthesis and characterisation is presented of the compounds [An(Tren^DMBS){Pn(SiMe₃)₂}] and [An(Tren^TIPS){Pn(SiMe₃)₂}] [Tren^DMBS=N(CH₂CH₂NSiMe₂Bu^t)₃, An=U, Pn=P, As, Sb, Bi; An=Th, Pn=P, As; Tren^TIPS=N(CH₂CH₂NSiPrⁱ₃)₃, An=U, Pn=P, As, Sb; An=Th, Pn=P, As, Sb]. The U−Sb and Th−Sb moieties are unprecedented examples of any kind of An−Sb molecular bond, and the U−Bi bond is the first two‐centre‐two‐electron (2c–2e) one. The Th−Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U−Bi complex is the heaviest 2c–2e pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An−An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U−Pn bonds degrade by homolytic bond cleavage, whereas the more redox‐robust thorium compounds engage in an acid–base/dehydrocoupling route.