Zwei neue Sulfidchloride der Lanthanide: Synthese und Kristallstruktur von Pr7S6Cl9 und Nd7S6Cl9

Two Novel Sulfide Chlorides of the Lanthanides: Synthesis and Crystal Structure of Pr₇S₆Cl₉ and Nd₇S₆Cl₉ The reactions of the elemental lanthanides (M = Pr and Nd, resp.) with sulfur and the respective trichlorides (MCl₃) in evacuated silica tubes (850 °C, 7 d) yield single-phase sulfide chlorides of the composition M₇S₆Cl₉ when appropriate molar ratios (4 : 6 : 3) of the reactants (M : S : MCl₃) are used. A slight excess of trichloride as a flux promotes the formation of lath-shaped transparent single crystals (Pr₇S₆Cl₉: pale green, Nd₇S₆Cl₉: pale violet) which prove to be water soluble and sensitive to hydrolysis. The crystal structure was determined from X-ray single-crystal data taking Nd₇S₆Cl₉ (monoclinic, P2/c (no. 13); a = 2425.0(9), b = 664.2(2), c = 691.8(2) pm, β = 97.43(3)°, Z = 2; R = 0.060, R_w = 0.048) as an example. According to Guinier powder data, Pr₇S₆Cl₉ crystallizes isotypically with a = 2441.6(9), b = 669.1(2), c = 696.3(2) pm, and β = 97.74(3)°. Thus four crystallographically independent cations (M³⁺) are present, each except for M2 coordinated by four S^2– but differing in the number of their next Cl^– neighbors. The figures of coordination are completed by four Cl^– about M1 (square antiprism, CN = 8) and by three Cl^– each about M3 and M4 (monocapped trigonal prisms, CN = 7, 2 Ç ). In contrast, M2 is coordinated by only two S^2– but five (plus one) Cl^– as bicapped trigonal prism (CN = 7 + 1). Eight crystallographically different anions, although indistinguishable by X-ray diffraction, exhibit coordination numbers of four (3 Ç S^2– and 1 Ç Cl^–) and three (4 Ç Cl^–) with respect to the cations. So PbO-analogous layers of the composition ²_∞{[(S6/7Cl_1/7)M_4/4]₇}⁸⁺ parallel (010) are formed, consisting of 6/7 of S^2– and only 1/7 of Cl^– as centering anions for the edge-shared (M³⁺)₄ tetrahedra for reasons of charge neutrality. These cationic layers are held together by alternatingly sheathed layers of Cl^– with only threefold coordinated anions.     

ChemInform Abstract: Conformations and Thermodynamic Properties of Sulfur Homocycles. Part 1. The S5, S6, S7, and S8 Molecules.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

La8Br7Ni4: ribbons of Ni hexagons in condensed La6 trigonal prisms

A ternary lanthanum bromide La 8Br 7Ni 4 was synthesized from La, LaBr 3, and Ni under an Ar atmosphere at 830 degrees C. It crystallizes in space group C2/ m (No. 12) with lattice constants a = 29.528(4) A, b = 4.0249(6), c = 8.708(1) A, and beta = 94.515(2) degrees . The structure features condensed Ni-centered La 6 trigonal prisms. The Ni atoms are bonded to each other to form ribbons of Ni hexagons. Band structure, bonding, and physical properties of the compound have been investigated.     

Total synthesis of (-)-(6S,7S,8S,9R,10S,2'S)-membrenone-A and (-)-(6S,7S,8S,9R,10S)- membrenone-B and structural assignment of membrenone-C

[reaction: see text] (-)-(6S,7S,8S,9R,10S,2'S)-Membrenone-A and (-)-(6S,7S,8S,9R,10S)-membrenone-B were prepared in 11 steps (3% and 2.4% overall yield, respectively). Key steps included a tin(II)-mediated aldol followed by a syn selective reduction, giving the C7-C9 stereocenters, a second chain extending aldol coupling, and a p-TsOH-promoted cyclization/dehydration giving the common gamma-dihydropyrone precursor. We have thus established that synthetic (-)-(6S,7S,8S,9R,10S,2'S)-membrenone-A, (-)-(6S,7S,8S,9R,10S)-membrenone-B, and (-)-(6S,7S,8S,9R,10S)-membrenone-C are the enantiomers of the natural products.     

Thermodynamic Characteristics of Ni3S2 Compound Formation

Published data on thermodynamic properties of the Ni₃S₂ compound in the liquid and solid states are compared and discussed.     

Preparation and physical properties of BiMo6S8 and SbMo6S8

The compounds Me₁Mo₆S₈ (Me = Bi, Sb) were prepared by low-temperature diffusion of Bi and Sb into the binary phase Mo₆S₈. The homogeneity range of the ternary elements is very narrow and centered about Me = 1.0, implying that the ternary metal is located at the origin position of the rhombohedral unit cell. The observed lattice parameters (BiMo₆S₈, a_h = 9.194, c_h = 11.325; SbMo₆S₈, a_h = 9.122, c_h = 11.282) are consistent with this hypothesis and suggest that these atoms enter the structure as trivalent cations. No superconducting transition is observed for these materials above 2 K. A small temperature-independent paramagnetism is present in the magnetic susceptibility of these compounds. The magnitude of this paramagnetism is less than that found in other ternary molybdenum chalcogenides with trivalent cations, suggesting that a reduced density of states is responsible for the observed lack of superconductivity. Attempts to prepare MeMo₆(S_1−xSe_x)₈ (Me = Sb and Bi) with x > 0 failed to yield ternary phases, instead producing mixtures of the unreacted ternary metal and the corresponding binary phase.     

High nuclearity in azido/oximate chemistry: Ni14 and Ni13 clusters with S = 6 and 9 ground states

In the present work, we report a family of Ni(14) and unprecedented Ni(13) clusters linked by end-on azido and oximato bridges. Ferrimagnetic response gives S = 6 and 9 ground states, resulting in the largest nuclearities and spins in nickel oximato chemistry.     

Enantiospecific synthesis of (6R,7S,8aR)-dihydroxyindolizidine and (6R,7R,8S,8aR)-trihydroxyindolizidine from D-glucose.

Enantiospecific syntheses of (6R,7S,8aR)-dihydroxyindolizidine (1) and (6R,7R,8S,8aR)-trihydroxyindolizidine (2) from readily available methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (5) are described.     

Synthesis of 11-hydroxydrim-8(9)-en-7-one and 11,12-dihydroxydrim-8(9)-en-7-one from drim-8(9)-en-7-one

A synthetic route to 11-hydroxydrim-8(9)-en-7-one and 11,12-hydroxydrim-8(9)-en-7-one, valuable key intermediates for the preparation of naturally occurring biologically active drimanic sesquiterpenoids, starting from easily available drim-8(9)-en-7-one was developed. 11-Hydroxydrim-8(9)-en-7-one was obtained by peracidic oxidation of the enol acetate of drim-8(9)-en-7-one. 11,12-Dihydroxydrim-8(9)-en-7-one was synthesized from drim-8(9)-en-7-one by two routes, namely, by a five-step procedurevia 11-hydroxydrim-8(9)-en-7-one and by bromination of drim-8(9)-en-7-one with NBS to give 11,12-dibromodrim-8(9)-en-7-one followed by its acetoxylation and deacetylation. Deceased Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 95–98, January, 2000.     

Synthesis of 11-hydroxydrim-8(9)-en-7-one and 11,12-dihydroxydrim-8(9)-en-7-one from drim-8(9)-en-7-one

A synthetic route to 11-hydroxydrim-8(9)-en-7-one and 11,12-hydroxydrim-8(9)-en-7-one, valuable key intermediates for the preparation of naturally occurring biologically active drimanic sesquiterpenoids, starting from easily available drim-8(9)-en-7-one was developed. 11-Hydroxydrim-8(9)-en-7-one was obtained by peracidic oxidation of the enol acetate of drim-8(9)-en-7-one. 11,12-Dihydroxydrim-8(9)-en-7-one was synthesized from drim-8(9)-en-7-one by two routes, namely, by a five-step procedurevia 11-hydroxydrim-8(9)-en-7-one and by bromination of drim-8(9)-en-7-one with NBS to give 11,12-dibromodrim-8(9)-en-7-one followed by its acetoxylation and deacetylation. Deceased Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 95–98, January, 2000.     

Enantiospecific synthesis of polhydroxylated indolizidines related to castanospermine: 1 (6R,7S,8aR)-6,7-dihydroxyindolizidine and (6R,7R,8S,8aR)-6,7,8-trihydroxyindolizidine.

Enantiospecific syntheses of (6R,7S,8aR)-6,7-dihydroxy-indolizidine (3) and (6R,7R,8S,8aR)-6,7,8-trihydroxy-indolizidine (4) from methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (7) are reported. The two synthetic indolizidines (3) and (4) have been tested against a wide range of enzymes.     

Calculation of electron densities for EuI 4f 7(8 S)6s7s

Using the non-relativistic Hartree-Fock computer code of Froese Fischer, calculations have been performed for all terms of the configuration 4f ⁷(⁸ S)6s7s of EuI. The results are compared with recent isotope shift and hyperfine structure measurements. The calculated electron charge densities reproduce, up to a scaling factor, the experimental field shifts.