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21.
Polyselenides with Long-chain Tetraalkylammonium Ions. Crystal Structure of Trimethyltetradecyl-ammonium Hexaselenide Na2Se2 and Na2Se react with various tetraalkylammonium halides in ethanol and in presence of grey selenium and catalytic quantities of iodine forming different polyselenides Sen2? (n = 3, 5—9). In the solutions equilibria of polyselenides seem to occur; cooling of saturated solutions causes crystallization of polyselenides with a composition depending on the cation. Tri- and pentaselenide are dark green. The higher members form black crystals, all compounds are sensitive to oxygen. The i.r. spectra are reported. [(CH3)3N(CH2)13CH3]2Se6 is characterized by a crystallographic structure determination with X-ray data: space group P21212, Z = 4, a = 5043, b = 734.2, c = 600.3 pm (986 observed independent reflexions. R = 0.072). The compound consists of trimethyl tetradecylammonium ions and angular Se62? chains of symmetry C2 with Se? Se bond lengths of 227 and 235 pm. 相似文献
22.
Template Reaction of Bis(acetylacetonato)-dioxo-molybdenum(VI) with Benzoylhydrazone By reaction of bis(acetylacetonato)-dioxo-molybdenum(VI) with benzoylhydrazine benzoylhydrazido(2?)-acetylacetonebenzoylhydrazonato(2?)-oxo-molybdenum(VI) was formed beside another species. The compound was characterized by mass spectrometry and X-ray structural analysis. Crystallographic data see ?Inhaltsübersicht”?. 相似文献
23.
Ingo Hartenbach Falk Lissner Tanja Nikelski Steffen F. Meier Helge Müller‐Bunz Thomas Schleid 《无机化学与普通化学杂志》2005,631(12):2377-2382
About Lanthanide Oxotantalates with the Formula MTaO4 (M = La – Nd, Sm – Lu) Besides being a by‐product of solid state syntheses in tantalum ampoules the lanthanide(III) oxotantalates of the formula MTaO4 can be easily prepared by sintering lanthanide sesquioxide M2O3 and tantalum(V) oxide Ta2O5 with sodium chloride as flux. Under these conditions two structure types emerge depending upon the M3+ cationic radius. For M = La – Pr the MTaO4‐type tantalates crystallize in the space group P21/c with lattice constants of a = 762(±1), b = 553(±4), c = 777(±4) pm, β = 101(±1)° and four formula units per unit cell. With M = Nd, Sm – Lu, the monoclinic cell dimensions (space group P2/c) shrink to the lattice constants like a = 516(±9), b = 551(±9), c = 534(±9) pm, β = 96.5(±0.3)° and there are only two formula units present. Both structures show a coordination sphere of eight oxygen atoms for the lanthanide trications shaped as distorted square antiprism for the structure with the larger lanthanides (in the following referred to as A‐type) and as trigonal dodecahedron for the structure with the smaller ones (called as B‐type in the following). The coordination environment about the Ta5+ cations can be described as a slightly distorted octahedron (CN = 6) for the A‐type structure of MTaO4 and a heavily distorted one (CN = 6) for the B‐type. The difference between the two types results from the interconnection of these [TaO6]7? octahedra. Whereas they are connected via four vertices to form corrugated layers according to parallel the bc‐plane in the A‐type, the octahedra of the B‐type MTaO4 structure share edges to built up zig‐zag chains along the c axis. 相似文献
24.
Dieter Seebach Thomas Weller Gerd Protschuk Albert K. Beck Marvin S. Hoekstra 《Helvetica chimica acta》1981,64(3):716-735
Preparation of 1,3-Diketones and of Nitro-diketones by (1:1)-Acylation of Lithium Enolates with Acyl Chlorides Slow addition of precooled solutions of lithium enolates in THF (Fig. 1) to solutions of equimolar amounts of acyl chlorides in the same solvent at temperatures between ? 80 and ? 100° furnishes 1, 3-diketones in acceptable to good yields (Tables 1?3). Even 3-nitropropionyl and 4-nitrobutyryl chloride can be employed for the (1:1)-acylation of enolates to give the synthetically useful 5- and 6-nitro-1, 3-diketones 13 and 25 , respectively. The scope and the limitations of this method of preparing 1, 3-diketones are given and are compared with alternative methods. 相似文献
25.
Rachel L. Weller 《Tetrahedron letters》2004,45(30):5807-5810
Ethyl (E)-4,5-dibromo-2-pentenoate readily reacts with an assortment of primary amines in the presence of DBU to afford the corresponding conjugated aziridines in good to moderate yields. That the reaction is compatible with a nucleoside-derived amine suggests a broad scope of application. 相似文献
26.
Lee A. Gerrard Mark T. Weller 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):m504-m505
Cocrystallization of the inorganic [BeF4]2? unit with the organic moiety [NH3CH2CH(NH3)CH3]2+ results in the three‐dimensional network of the title compound, (C3H12N2)[BeF4] or C3H12N22+·BeF42?, created by hydrogen bonds between the protonated ammonium groups and the highly electronegative F atoms of the anion. The structure is described in terms of layers related to each other by crystallographic centres of symmetry. 相似文献
27.
28.
Addition of H2 (4 atm at 298 K) to [Rh(nbd)(PR3)2][BAr(F)4] [R = Cy, iPr] affords Rh(III) dihydride/dihydrogen complexes. For R = Cy, complex 1a results, which has been shown by low-temperature NMR experiments to be the bis-dihydrogen/bis-hydride complex [Rh(H)2(eta2-H2)2(PCy3)2][BAr(F)4]. An X-ray diffraction study on 1a confirmed the {Rh(PCy3)2} core structure, but due to a poor data set, the hydrogen ligands were not located. DFT calculations at the B3LYP/DZVP level support the formulation as a Rh(III) dihydride/dihydrogen complex with cis hydride ligands. For R = iPr, the equivalent species, [Rh(H)2(eta2-H2)2(P iPr3)2][BAr(F)4] 2a, is formed, along with another complex that was spectroscopically identified as the mono-dihydrogen, bis-hydride solvent complex [Rh(H)2(eta2-H2)(CD2Cl2)(P iPr3)2][BAr(F)4] 2b. The analogous complex with PCy3 ligands, [Rh(H)2(eta2-H2)(CD2Cl2)(PCy3)2][BAr(F)4] 1b, can be observed by reducing the H2 pressure to 2 atm (at 298 K). Under vacuum, the dihydrogen ligands are lost in these complexes to form the spectroscopically characterized species, tentatively identified as the bis hydrides [Rh(H)2(L)2(PR3)2][BAr(F)4] (1c R = Cy; 2c R = iPr; L = CD2Cl2 or agostic interaction). Exposure of 1c or 2c to a H2 atmosphere regenerates the dihydrogen/bis-hydride complexes, while adding acetonitrile affords the bis-hydride MeCN adduct complexes [Rh(H)2(NCMe)2(PR3)2][BAr(F)4]. The dihydrogen complexes lose [HPR3][BAr(F)4] at or just above ambient temperature, suggested to be by heterolytic splitting of coordinated H2, to ultimately afford the dicationic cluster compounds of the type [Rh6(PR3)6(mu-H)12][BAr(F)4]2 in moderate yield. 相似文献
29.
Dichloro Acetylene as Complex Ligand. Crystal Structure of PPh4[WCl5(C2Cl2)] · 0.5 CCl4 Tungsten hexachloride and dichloro acetylenediethyletherate react in boiling CCl4 in presence of C2Cl4 as reducing agent forming [Et2O · WCl4(C2Cl2)]. In vacuo the complex looses ether giving the dichloro acetylene complex [WCl4(C2Cl2)]2 which is dimeric with chloro bridges. Both complexes react with tetraphenylphosphonium chloride to form PPh4[WCl5(C2Cl2)] which is equally prepared by ligand exchange of PPh4[WCl5(C2I2)] with silver chloride. All dichloro acetylene complexes are red to brown crystalline solids sensitive to moisture, and are thermally and mechanically very stable compared with the highly explosive dichloro acetylene. The compounds are characterized by their i.r. spectra; [Et2O · WCl4(C2Cl2)] was additionally investigated by 13C-nmr spectroscopy. PPh4[WCl5(C2Cl2)] · 0.5 CCl4 formes dark brown crystals; according to the structural investigation by X-ray diffraction methods the compound crystallizes orthorhombic in the space group Pbca with 8 formula units per unit cell (1317 observed, independent reflexions, R = 0.049). The cell dimensions are a = 1702 pm, b = 1675 pm and c = 2228 pm. The compound consists of [WCl5(C2Cl2)]? anions and PPh4⊕ cations including CCl4 molecules without bonding interactions. The tungsten atoms are seven-coordinated by five chlorine atoms and two carbon atoms. The dichloro acetylene ligand is bonded symmetrically side-on and has a C? C bond length of 128 pm. The W? C distances are 201 pm, the four equatorial Cl atoms have W? Cl bond lengths of 234 pm whereas the chlorine atom in trans-position to the W? C2 group is situated in a distance of 244 pm. 相似文献
30.
Complexes of Vanadium and Titanium with Salicylaldehyde benzoylhydrazone and 2-(2′-Hydroxyphenyl)-8-quinolinol. Crystal Structure of μ-Oxo-bis[oxo{2-(2′-hydroxyphenyl)-8-quinolinato(2-)}-vanadium(V)] . By reaction of titanium(IV)-isopropoxide and bis(acetylacetonato)-oxovanadium(IV) with salicylaldehyde benzoylhydrazone and 2-(2′hydroxyphenyl)-8-quinolinol, respectively, the metal complexes of the tridentate diacidic ligands were synthesized and characterized mass spectrometrically. The mass spectra of the titanium compounds correspond to the expected bisligand complexes whereas several species are demonstrable in the case of vanadium. Crystals of μ-oxo-bis[oxo{2-(2′-hydroxyphenyl)-8-quinolinolato(2-)}-vanadium(V)] were isolated and characterized by X-ray structural analysis. The complex exhibits C2 symmetry, accordingly the μ2-oxygen atom is situated on the 4 axis. The VOV bridge is angular with the unusually small bond angle of 107.3°. The coordination polyhedron is distorted octahedral. The compound additionally contains one molecule of chloroform per formula unit which is disordered in two positions. Crystallographic data see “Inhaltsübersicht”. 相似文献