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On Seleno- and Telluroarsenites, -antimonites, and -bismutites The new compounds NaAsSe2, NaSbSe2, NaSbTe2, and NaBiTe2 have been prepared and their structures determined. NaSbSe2, NaSbTe2, and NaBiTe2 build up the NaCl structure with the following lattice constants: NaSbSe2: a = 596.6(2) pm, NaSbTe2: a = 631.7(2) pm, NaBiTe2: a = 636.6(3) pm. NaAsSe2 crystallizes orthorhombic with a = 583 ± 1pm, b = 2427 ± 5 pm, c = 1182 ± 2 pm, Pbca. In the structure there are distorted trigonal AsSe3 pyramids which are connected by corners to chains. 相似文献
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Fritz Eiden 《Chemie in Unserer Zeit》2006,40(1):12-19
Numerous species of blister beetles use cantharidin in their blood as a protecting and attracting agent. From antiquity to the 20th century these beetles (and later the substance cantharidin itself) have been utilized as a medicine and an aphrodisiac. The advantages were however very limited, because of cantharidins high toxicity. From the first isolation of the active substance to the unravelling of its structure and the discovery of viable synthetic methods it took 150 years. Cantharidin has recently found growing interest among molecular biologists, pharmacologists and chemists, due to its property of inhibiting enzymes (protein phosphatases) which regulate cellular metabolism. 相似文献
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Elmar Hecht 《无机化学与普通化学杂志》2000,626(7):1642-1646
Preparation, Properties, and Molecular Structures of Dimethylmetal Alkoxides and Amides of Aluminium and Gallium Dimethylaluminium‐ ( 1 ) and Dimethylgallium‐o‐methoxyphenyl‐1‐ethoxide ( 2 ) were obtained by reaction of Me3Al and Me3Ga respectively with o‐Methoxyphenyl‐1‐ethanol in n‐pentane. Dimethylaluminium‐ ( 3 ) and dimethylgallium‐o‐methoxyphenyl‐2‐ethylamide ( 4 ) were prepared by treatment of Me2AlCl and Me2GaCl respectively with Lithium‐o‐methoxyphenyl‐2‐ethylamide. Trimethylgallium‐o‐methoxyphenylmethylamine‐Adduct ( 5 ) was isolated using reaction of Me3Ga with the corresponding amine. The compounds were characterised by 1H‐, 13C‐, and 27Al n.m.r. spectroscopy. The molecular structures of 2 and 5 were determined by X‐ray diffraction. Compounds 1 – 4 form brigded dimeric molecules. The bond distances of the central Ga2O2 ring in 2 correspond to those of compounds of similar structure. 相似文献
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DySBr and DySI – Synthesis, Crystal Structure, and Magnetism By reaction of Dy2S3 with Dy metal and Br2 (I2) at 750°C (900°C), single phase crystalline DySBr (DySI) has been synthesized. Crystal structure refinement of DySBr confirms the FeOCl-type structure (R = 0.049; space group Pmmn, Z = 2, lattice parameters (in Å): a = 5.349(2), b = 4.079(2), c = 8.066(2)) which is also ascertained for DySI (R = 0.059; lattice parameters (in Å): a = 5.320(2), b = 4.168(1), c = 9.224(5)). The magnetic susceptibilities (temperature range 3.4 K – 295 K) can be described on the basis of simple models (cubic crystal field, molecular field approximation) above 5 K and 15 K respectively. The deviations at low temperature are assumed to be related essentially to Dy—Dy exchange interactions which are not adequately described with the molecular field approach. 相似文献
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Dimethyl Earth‐Metal Heterocycles – Derivatives of Trimethyl‐silylated, ‐germylated, and ‐stannylated Phosphanes and Arsanes – Syntheses, Spectra, and Structures The organo earth‐metal heterocycles [Me2MIII–E(MIVMe3)2]n with MIII = Al, Ga, In; E = P, As; MIV = Si, Ge, Sn and n = 2, 3 (Me = CH3) have been prepared from the dimethyl metal compounds Me2MIIIX (X = Me, H, Cl, OMe, OPh) and the pnicogen derivatives HnE(MIVMe3)3–n (n = 0, 1) according to known preparation methods. The mass, 1H, 13C, 31P, 29Si, 119Sn nmr, as well as the ir and Raman spectra have been discussed comparatively; selected representatives are characterized by X‐ray structure analyses. The dimeric species with four‐membered (E–MIII)2 rings are isotypic and crystallize in the triclinic space group P1, the trimer [Me2In–P(SnMe3)2]3 with a strongly puckered (In–P)3‐ring skeleton crystallizes with two formula units per cell in the same centrosymmetric triclinic space group. 相似文献
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Claus Priesner 《Chemie in Unserer Zeit》2009,43(4):214-223
The article shows how deceitful alchemists betrayed their victims from the 16th to the 20th century. A number of biographical sketches demonstrate, how they hoodwinked their victims and what tricks they employed with their seemingly successful transmutations. It is also shown, why people again and again where willing to believe the goldmakers' promises of tons of gold. 相似文献
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Dieter Sorsche 《Nachrichten aus der Chemie》2011,59(9):916-917
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Trimethylsilyl and Trimethylstannyl Esters of the Trithiophosphonic Acids; Preparation, Protolysis, and Further Reactions The organotrithiophosphonic acid bis(trimethylsilyl) esters RP(S)(SSiMe3)2, R = Ph ( 1a ), R = t-Bu ( 1b ) and R = Me ( 1c ) are formed in high yield from the organo-bis(trimethylsilyl)-phosphanes RP(SiMe3)2 by the addition of three sulfur atoms (3/8 S8) in toluene solution. 1b has also been prepared by reacting disodium tert-butyltrithiophosphonate, Na2t-BuP(S)S2 ( 2 ) with SiMe3Cl. Analogous reactions can be used for the preparation of the stannyl esters RP(S)(SSnMe3)2, R = t-Bu ( 5a ) and R = Me ( 5b ). More favorable, however, these compounds are synthesized from the corresponding silyl esters 1b, c and SnMe3Cl or, as has been shown in the case of 5a , by reacting dithiophosphonic acid anhydrides (RP(S)S)2 with (SnMe3)2S. Low temperature solvolysis of the silyl esters 1b, c with water or methanol results in the free organotrithiophosphonic acids RP(S)(SH)2, R = t-Bu ( 6a ) and R = Me ( 6b ), which can be isolated as white solids at —30°C. Contrary to the sodium salt 2 and the stannyl esters 5a, b , the acids 6a, b , and, to a smaller extent, the silyl esters 1a—c are thermally not stable towards decomposition into the thioanhydrides (RP(S)S)2. The silyl and stannyl esters 1a—c and 5a, b , respectively, are capable of cleaving the ether linkage of tetrahydrofuran, which in the case of 1b leads to the quantitative formation of t-BuP(S)[S(CH2)4OSiMe3]2 ( 9 ). 1b, c and 5a, b react with Cl2 and Br2 forming the 3,6-diorgano-3,6-dithio-1,2,4,5,3,6-tetrathiadiphosphorinanes (RP(S)S2)2, R = t-Bu ( 7a ) and R = Me ( 7b ). 相似文献
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On Calcium Bromated and Iodates – Crystal Structure, X-Ray, IR and Raman Spectroscopical and Thermoanalytical Investigations The phase relationships (and both decomposition and disproportionation)of bromates and iodates of alkaline earth metals are studied by means of thermal analyses (DTA, DSC, TG) and (high-temperature) X-Ray, IR-, and (high-temperature) Raman spectroscopic measurements. The following compounds have been established: Ca(IO3)2 · 6 H2O oF 216, the isotypic Ca(BrO3)2 · H2O and Ca(IO3)2 · H2O mP 48, Ca(IO3)2 I (Lautarit) mP 36, Ca(IO3)2 II and Ca(BrO3)2. The Crystal structure of Ca(IO3)2 · H2O (brüggenite) (space group P21/c, Z = 4) has been determined by single crystal X-ray diffraction (MoKα). The final R value for 3888 reflections with Io > 3σ1 is 0.0487. The structures of bromates and iodates of alkaline earth metals known so far are discussed with respect to the energetic (mode frequencies) and geometric (bond lengths) distortion of the XO3–ions as well as the strengths of H-bonds present in the respective hydrates. 相似文献
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Hydrothermal Synthesis and Crystal Structure of the Coinage Metal Mercury Chalcogenide Halides CuHgSeBr, AgHgSBr, and AgHgSI The hydrothermal reaction of CuBr and HgSe in concentrated aqueous HBr as solvent at 285 °C yields red crystals of CuHgSeBr, the hydrothermal reaction of AgX (X = Br, I) and HgS in half‐concentrated aqueous HX (X = Br, I) as solvent at 300/400 °C yields yellow crystals of AgHgSBr and AgHgSI. The compounds crystallize isotypically (orthorhombic, Pmma, a = 1020.1(3) pm, b = 431.2(1) pm, c = 925.6(3) pm for CuHgSeBr, a = 964.8(8) pm, b = 466.1(4) pm, c = 942.6(6) pm for AgHgSBr und a = 1015.9(2) pm, b = 464.77(5) pm, c = 984.9(2) pm for AgHgSI, Z = 4). The structures consist of plane folded Hg–Y chains connected by pairs of distorted Y2X2 terahedra sharing the X–X‐edge (M = Cu, Ag; X = Br, I; Y = S, Se). Atoms of the monovalent metals M have a strongly distorted tetrahedral coordination of two halogen and two chalcogen atoms. The new structure type shows distinct differences in the arrangement of the Hg–Y chains in comparision to the already known CuHgSeCl, but represents the superposition structure of the order‐disorder phase γ‐Hg3S2Cl2. 相似文献