Unequivocal syntheses of 6-methyl- and 6-phenylisoxanthopterin

Although 6-methyl- ( 1 ) and 6-phenylisoxanthopterin ( 2 ) have previously been synthesized, the requirement of high purity necessary for immunological testing has necessitated our development of the first reported synthesis of these compounds by unequivocal methods. In the process of so doing four new pyrazines, ethyl 3-amino-5-chloro-6-methyl-2-pyrazinecarboxylate ( 11 ), N,N-dimethyl-N'-(6-chloro-3-cyano-5-phenylpyrazin-2-yl)methanimidamide ( 16 ), 2-amino-3-ethoxycarbonyl-5-phenylpyrazine 1-oxide ( 19 ), and ethyl 3-amino-5-chloro-6-phenyl-2-pyrazinecarboxylate ( 20 ) were synthesized. Four new pteridines, 7-methoxy-6-methyl-2,4-pteridinediamine ( 7 ), 7-methoxy-6-phenyl-2,4-pteridinediamine ( 17 ), 2-amino-7-ethoxy-6-methyl-4(3H)-pteridinone ( 12 ), and 2-amino-7-ethoxy-6-phenyl-4(3H)-pteridinone ( 21 ) have also been synthesized enroute to these isoxanthopterins.     

Karpoxanthin und 6-Epikarpoxanthin

Karpoxanthin and 6-Epikarpoxanthin A tetrahydroxy-β,β-carotene previously isolated in minute amounts from ripe hips of Rosa pomifera was now identified as (3S,5R,6R,3′R)-5,6-dihydro-β,β-carotene-3,5,6,3′-tetrol ( 2 ). Acid hydrolysis of (9Z)-antheraxanthin ( 3 ) gave 2 and its C(6)-epimer 4 . Tetrol 2 is named karpoxanthin.     

Röntgenstrukturuntersuchungen an den polymorphen Elpasolithen K2LiAlF6 und Rb2LiGaF6

X-Ray Structural Studies of the Polymorphic Elpasolites K₂LiAlF₆ and Rb₂LiGaF₆ At single crystals of low (LT) and high temperature (HT) modifications of K₂LiAlF₆ and of Rb₂LiGaF₆, synthesized at normal pressure (NP), the crystal structures were refined. LT-K₂LiAlF₆ is a cubic elpasolite (Fm3m, Z = 4, a = 784.2(1) pm; Al–F: 181.2(1) pm), HT-K₂LiAlF₆ and NP-Rb₂LiGaF₆ are isostructural with the hexagonal-rhombohedral type of Cs₂NaCrF₆ (R3m, Z = 6, a = 561.7(1) resp. 586.3(1), c = 2757.6(6) resp. 2856.3(5) pm; mean values Al–F: 180.5 resp. Ga–F: 189.3 pm). A cubic high pressure modification (HP) of Rb₂LiGaF₆ was obtainable as a powder only (a = 820.8(2) pm). The relations of distances between LT/HT and HP/NP polymorphs of elpasolites are compared and discussed.     

Neue Synthesen und Kristallstrukturen von Bis(fluorphenyl)quecksilber,Hg(Rf)2 (Rf = C6F5, 2, 3, 4, 6‐F4C6H, 2, 3, 5, 6‐F4C6H, 2, 4, 6‐F3C6H2, 2, 6‐F2C6H3)

New Syntheses and Crystal Structures of Bis(fluorophenyl) Mercury, Hg(R_f)₂ (R_f = C₆F₅, 2, 3, 4, 6‐F₄C₆H, 2, 3, 5, 6‐F₄C₆H, 2, 4, 6‐F₃C₆H₂, 2, 6‐F₂C₆H₃) Bis(fluorophenyl) mercury compounds, Hg(R_f)₂ (R_f = C₆F₅, C₆HF₄, C₆H₂F₃, C₆H₃F₂), are prepared in good yields by the reactions of HgF₂ with Me₃SiR_f. The crystal structures of Hg(2, 3, 4, 6‐F₄C₆H)₂ (monoclinic, P2₁/n), Hg(2, 3, 5, 6‐F₄C₆H)₂ (monoclinic, C2/m), Hg(2, 4, 6‐F₃C₆H₂)₂ (monoclinic, P2₁/c) and Hg(2, 6‐F₂C₆H₃)₂ (triclinic, P1) are described.     

Pr6C2‐Doppeltetraeder in Pr6C2Cl10 und Pr6C2Cl5Br5

Pr₆C₂‐Bitetrahedra in Pr₆C₂Cl₁₀ and Pr₆C₂Cl₅Br₅ The compounds Pr₆C₂Cl₁₀ and Pr₆C₂Cl₅Br₅ are prepared by heating stoichiometric mixtures of Pr, PrCl₃, PrBr₃ and C in sealed Ta capsules at 810 ? 820 °C. They form bulky transparent yellow to green and moisture sensitive crystals which have different structures: space groups C2/c, (a = 13.687(3) Å, b = 8.638(2) Å, c = 15.690(3) Å, β = 97.67(3)° for Pr₆C₂Cl₁₀ and a = 13.689(1) Å, b = 10.383(1) Å, c = 14.089(1) Å, β = 106.49(1)° for Pr₆C₂Cl₅Br₅). Both crystal structures contain C‐centered Pr₆C₂ bitetrahedra, linked via halogen atoms above edges and corners in different ways. The site selective occupation of the halogen positions in Pr₆C₂Cl₅Br₅ is refined in a split model and analysed with the bond length‐bond strength formalism. The compound is further characterized via TEM investigations and magnetic measurements (μ_eff = 3.66 μ_B).     

Copolymeric cyclodextrin polysiloxane stationary phases prepared from 6A,6C- and 6A,6D-dialkenyl-substituted β-cyclodextrin

The syntheses of four new β-cyclodextrin-hexasiloxane copolymers from heptakis(2,3-di-O-methyl)-β-cyclodextrin (2) by multi-step processes are described. 6^A,6^C-Di-O-[p,p'-methylenebis(benzenesulfonyl)]hetakis(2,3-di-O-methyl)β-cyclodextrin (3) , which was prepared by the reaction of 2 with p,p'-methylenebis-(benzenesulfonyl chloride), is a key intermediate for the preparation of permethylated 6^A,6^C-bisalkenyl-β-cyclodextrins 5, 6 , and 9. Permethylated 6^A,6^C-bissulfonate ester 4 , which was obtained from 3 by a methylation reaction under mild conditions, was reacted with sodium allyloxide or sodium ω-undecenyloxide to produce permethylated 6^A,6^C-bisallyl- (or bis-ω-undecenyl)-β-cyclodextrin 5 or 6 or was hydrolyzed with 2% sodium amalgam in methanol to yield diol 7. Compound 7 was oxidized with periodinane, followed by Wittig's reaction with methyltriphenylphosphonium iodide to give permethylated 6^A,6^C-dideoxy-6^A,6^C-dimethylene-β-cyclodextrin (9). Treatment of 2 with p,p'-methylenebis(benzenesulfonyl chloride) or p,p'-biphenyldisulfonyl chloride gave bissulfonate esters 10 or 11 , respectively. Both of them were treated with sodium p-allyloxy-phenoxide in DMF, followed by methylation, to form permethylated 6^A,6^D-di-O-(p-allyloxyphenyl)-β-cyclo-dextrin (16). Bisalkenes 5, 6, 9 and 16 were copolymerized with α,ω-dioctyldecamethylhexasiloxane by a hydrosilylation process to give the cyclodextrin-containing copolymers 17–20.     

Synthesis and Properties of Rb6Mn2O6

Rb₆Mn₂O₆ was prepared via the azide/nitrate route. Stoichiometric mixtures of the precursors (Mn₃O₄, RbN₃ and RbNO₃) were heated in a special regime up to 500 °C and annealed at this temperature for 75 h in silver crucibles. Single crystals have been grown by annealing a mixture with a slight excess of rubidium components at 450 °C for 500 h. According to the single crystal structure analysis, Rb₆Mn₂O₆ is isotypic to K₆Mn₂O₆, and crystallizes in the monoclinic space group P2₁/c with a = 6.924(1) Å, b = 11.765(2) Å, c = 7.066(1) Å, β = 99.21(3)°, 2296 independent reflections, R₁ = 5.23 % (all data). Manganese is tetrahedrally coordinated and two tetrahedra are linked by sharing a common edge, forming a dimer [Mn₂O₆]⁶⁻. The magnetic behavior has been investigated.     

The Simultaneous Oxidation of Tellurium and Transition Metals by AsF5 – Syntheses and Crystal Structures of [M(SO2)6](Te6)[AsF6]6 (M = Ni,Zn) and [Cd(SO2)2][AsF6]2

The reactions of elemental nickel and tellurium and of ZnTe with excess AsF₅ in liquid SO₂ yield [M(SO₂)₆](Te₆)[AsF₆]₆ (M = Ni, Zn) as orange crystals. The crystal structure determinations (triclinic, , M = Ni: a = 1632.59(2), b = 1795.06(1), c = 1822.97(2) pm, α = 119.11(4), β = 90.78(4), γ = 106.28(4)°, V = 4408.24(8)·10⁶pm³, Z = 4) show the two compounds to be isotypic. The structures are made up of discrete [M(SO₂)₆]²⁺ complexes, Te₆⁴⁺ clusters and octahedral [AsF₆]^? ions. In the [M(SO₂)₆]²⁺ complexes the metal ions are surrounded octahedrally by six SO₂ molecules bound via the O atoms. The Te₆⁴⁺ polycations are of trigonal prismatic shape with short Te–Te bonds within the triangular faces (270 pm) and long Te–Te bonds along the edges parallel to the pseudo C₃ axes of the prisms (312 pm). The arrangement of the ions is related to the Li₃Bi structure type. [M(SO₂)₆]²⁺ complexes and Te₆⁴⁺ polycations together form a distorted cubic closest packing with all tetrahedral and octahedral interstices filled by [AsF₆]^? ions. The analogous reaction starting from CdTe did not yield a compound containing simultaneously [Cd(SO₂)_n]²⁺ complexes and tellurium polycations but instead Te₆[AsF₆]₄ · 2 SO₂ besides [Cd(SO₂)₂][AsF₆]₂ were obtained. It crystallizes isotypically to [Mn(SO₂)₂][AsF₆]₂ (Mews, Zemva, 2001) (orthorhombic, Fdd2, a = 1534.96(3), b = 1812.89(3), c = 892.28(3) pm, V = 2483·10⁶ pm³, Z = 4).     

Organoruthenaborane Chemistry. X. The SM2-catalysed formation of [ l-(η6-C6Me6)-isocloso-RuB9H9], and some B-phenylamino derivatives. NMR and X-ray diffraction studies

The action of SMe₂ on the ten-vertex nido-ruthenaborane [6-(η⁶-C₆Me₆)RuB₉H_l3] ( 1 ) provides a high-yield route to the unsubstituted isocloso-ruthenaborane [1-(η⁶-C₆Me₆)RuB₉H₉] (2). The benzene analogue [1-(η⁶-C₆Me₆)RuB₉H₉] is prepared similarly. By contrast, reaction of (1) with PhNH₂ gives a variety of B-phenylamino isocloso derivatives, including orange crystals of [1-(η⁶-C₆Me₆)-2-(PhNH)-isocloso-1-RuB 9 H₈] ( 3 ), red-orange [1-(η⁶-C₆Me₆)-2,3-(PhNH)₂-isocloso-1-RuB₉H₇] ( 4 ) and dark-red [1-(η⁶-C₆Me₆)-5,6,7-(PhNH)₃-isocloso-1-RuB₉H₆] ( 5 ). Detailed ¹H and ¹¹B nmr properties of these various compounds are described. The structure of ( 3 ) has been established by a single-crystal X-ray diffraction study of the solvate [1-(η⁶-C₆Me₆)-2-(PhNH)-isocloso-1-RuB₉H₈] · 1/2 CH₂Cl₂; the crystals were monoclinic, space group C2/c, with a = 1895.1(3), b = 1556.6(3), c = 1716.4(3) pm, β = 104.37(1)° and z = 8.     

Synthesis of New Sialidase Inhibitors, 6-Amino-6-Deoxysialic Acids

The synthesis of the 6-amino-6-deoxysialic-acid analogues 4, 5 , and 6 , is described. Mitsunobu reaction of the 1-C-nitroglycal 8 , (PPh₃, HCOOH, DEAD) gave the formiate 10 with inversion of configuration at C(3) (Scheme 2). Treatment of 10 with aq. NH₃ and subsequent protection of the amino function gave the imines 14 and 15 (Scheme 3), which were transformed into the triflates 17 . Substitution by azide, deprotection, and N-acetylation gave the anormeric 2-acetamido-3-azido-1-deoxy-1-nitro-D -mannoses 16 and the enol ether 18 . Chain elongation of the nitro azides 16 followed by hydroylsis gave the nonulosonates 20/22 , which upon reduction yielded the diols 23 and 24 , respectively (Scheme 4). The diol 23 was transformed into the sialic-acid analogues 5, 6 , and 32 by ozonolysis, transfer hydrogenation, hydorgenolysis, and deprotection (Scheme 5), and the diol 24 into 4 by a similar reaction sequence. The sialic-acid analogues 4 and 6 inhibit bacterial and viral sialidases competitively. The inbibitor constants for this enzyme from Vibrio cholerae are 0.12 mm for 4 and 0.19 mm for 6 , respectively. The activity of fowl plague virus sialidase was reduced by 17% and 36% under the influence of 4 and 6 , respectively, at a concentration of 0.1 mM . Compound 5 was inactive.     

Synthesen und Charakterisierung von [Ni(tBuAs)6] und [Pd(tBuAs)6]

Syntheses and Characterization of [Ni(tBuAs)₆] and [Pd(tBuAs)₆] The reduction of tBuAsCl₂ with magnesium in the presence of NiCl₂ or PdCl₂ yields the complexes [Ni(tBuAs)₆] ( 2 ) and [Pd(tBuAs)₆] ( 3 ). The structure of ( 2 ) was determined by X-ray single crystal structure analysis. ( 2 ) consists of the sixmembered ring (tBuAs)₆ in chair conformation with the nickel atom in the center of this ring.     

MC-SCF and CI calculations on four isomers of Si6H6

The four isomers of Si₆ H₆, hexasilabenzene ( 1 ), hexasilaprismane ( 2 ), hexasila-Dewar benzene ( 3 ), and tris-(disilanediyl) ( 4 ), have been investigated, using highly correlated wavefunctions in conjunction with a local pseudopotential approach. At the Hartree-Fock level 1 (D_6h), 2 (D_3h), and 3 (C_2v) are established as minima by means of the harmonic vibrational frequencies. Inclusion of the most important correlation corrections via CI however, provokes a significant puckering of 1 resulting in a D_3d structure, 7.1 kJ/mol below the planar conformer. The detailed analysis shows unambiguously that the propensity to puckering is due solely to the correlation contributions from the σ framework while correlation of the π electrons is of little relevance. Isomer 2 turns out to be the most stable of the investigated isomers lying 41 kJ/mol below 1 (D_3d). Isomers 3 and 4 are more than 100 kJ/mol higher in energy. The Si? Si bond energies of 1 and 2 are determined as 251 and 176 kJ/mol, respectively.     

Caesiumchromhalogenide Cs3CrCl6, Cs3Cr2Cl9 und Cs3CrBr6 – Darstellung,Eigenschaften, Kristallstruktur

Cesium Chromium Halides Cs₃CrCl₆, Cs₃Cr₂Cl₉, and Cs₃CrBr₆ – Preparation, Properties, Crystal Structure The crystal structures of Cs₃CrCl₆ and Cs₃Cr₂Cl₉ were determined and redetermined by X‐ray single‐crystal studies (space group Pnnm, Z = 6, a = 1115.6(2) pm, b = 2291.3(5) pm, c = 743.8(1) pm, R_f = 7.73%, 1025 unique reflections with I > 2σ(I) (Cs₃CrCl₆); P6₃/mmc, Z = 2, a = 721.7(2) pm und c = 1791.0(1) pm; R_f = 2.06%, 395 unique reflections with I > 2.5σ(I) (Cs₃Cr₂Cl₉). The structure of Cs₃CrCl₆ consists of two different isolated CrCl₆ octahedra and five crystallographic different Cs⁺ ions. The CrCl₆ octahedra form ropes in the direction [001]. Because of orientational disordering of the Cr(1)Cl₆ octahedra and the an only half‐occupation of some cesium and chlorine sites Cs₃CrCl₆ is strongly disordered in direction of the (020) plane. The ionic conductivity of Cs₃CrCl₆, which was expected owing to the great disorder, however, is with 7.3 × 10^–5 Ω^–1 cm^–1 at 740 K relatively small. The compound Cs₃CrBr₆, which was firstly prepared by quenching stoichiometric amounts of CsBr and CrBr₃ from 833 K, is metastable at ambient temperature. It is probably isostructural to Cs₃CrCl₆ as shown by X‐ray powder photographs.     

Crystal and molecular structures of binuclear caesium complexes with 1,3-calix[4]-bis-crown-6 and 1,3-calix[4]-bis-benzo-crown-6

The crystal structures of two binuclear complexes between caesium and 1,3-calix[4]-bis-crowns have been determined. Cs₂ Bis-benzoC6(NO₃)₂. 3CHCl₃ (1) in whichBis-benzoC6 is 1,3-calix[4]-bis-benzo-crown-6, crystallizes in the orthorhombic system: space groupPca2 ₁ a=19.513(10),b=15.382(5),c=23.708(9) Å,V=7116(5) ų,Z=4. Refinement led to a final conventionalR value of 0.065 for 2321 reflections. The structure of (1) is analogous to those already reported withBis-C6, (in whichBis-C6 is, 1,3-calix[4]-bis-crown-6) and NO ₃ ^– as a counter-ion. Cs₂ Bis-C6(NCS)₂ (2) crystallizes in the monoclinic system: space, groupC2 a=36.57(2),b=11.47(1),c=13.65(1) Å, =109.03(5)°.,V=5415(6) ų,Z=4. Refinement led to a final conventionalR value of 0.063 for 2227 reflections. Compound (2) is made of dimers bridged by a disordered NCS^– ion. The crown ether chain conformations are discussed. Supplementary data relating to this article (atomic coordinates, anisotropic displacement parameters, bond distances and angles and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82199 (52 pages).     

Synthese,Kristallstrukturen und Magnetismus von (Hg6As4)[MoCl6]Cl, (Hg6As4)[TiCl6]Cl und (Hg6As4)[TiBr6]Br

Polycationic Hg–As Frameworks with Trapped Anions. II Synthesis, Crystal Structure, and Magnetism of (Hg₆As₄)[MoCl₆]Cl, (Hg₆As₄)[TiCl₆]Cl, and (Hg₆As₄)[TiBr₆]Br (Hg₆As₄)[MoCl₆]Cl is obtained by reaction of Hg₂Cl₂, Hg, As, and MoCl₄ in closed, evacuated glass ampoules in a temperature gradient 450 → 400 °C in form of dark red cubelike crystals. (Hg₆As₄)[TiCl₆]Cl and (Hg₆As₄)[TiBr₆]Br are also formed in closed, evacuated ampoules from Hg₂X₂ (X = Cl, Br), Hg, As, and Ti metal at 275 °C and 245 °C in form of dark green and black crystals, respectively. All three compounds are air and light sensitive. They crystallize isotypically (cubic, Pa 3, a = 1207.8(4) pm for (Hg₆As₄)[MoCl₆]Cl, a = 1209.4(3) pm for (Hg₆As₄)[TiCl₆]Cl, a = 1230.9(3) pm for (Hg₆As₄)[TiBr₆]Br, Z = 4). The structures consist of a three‐dimensionally connected Hg–As framework which is made up of As₂ groups (As–As distance averaged 242 pm) each connected via six Hg atoms to six neighbouring As₂ groups. There are two cavities of different size in the polycationic framework. The bigger cavity is filled with [MoCl₆]^3–, [TiCl₆]^3–, and [TiBr₆]^3– ions of nearly ideal octahedral shape, the smaller cavity with discrete halide ions. The magnetic properties of the two Ti containing compounds are in accordance with a d¹ paramagnetism. The temperature dependence and the magnitude of the magnetic moment can be interpreted with consideration of the spin‐orbit coupling. The so far known representatives of this structure type can be characterised by the ionic formula (Hg₆Y₄)⁴⁺[MX₆]^3–X^– (Y = As, Sb; M = Sb³⁺, Bi³⁺, Mo³⁺, Ti³⁺; X = Cl, Br).     

Synthesis and Structure Determination of Ag5HgSbO6, Comparison with AgHg3SbO6 and Ag5Pb2O6

From solid state reactions of Ag₂O, HgO, and Sb₂O₃ at high temperatures under elevated oxygen pressures a new silver mercury antimonate, Ag₅HgSbO₆, has been obtained. According to a single crystal structure determination Ag₅HgSbO₆ crystallizes in space group P$\bar{3}$ 1c (no. 163) with a = 5.9263(4), c = 12.3023(7) Å, V = 374.18(4) ų, Z = 2, 498 independent reflections, R1 = 0.030, wR2 = 0.059 (I ≥ 2 σ (I). Ag₅HgSbO₆ consists of HgSbO₆ layers, analogous to BiI_3, which are separated by Kagome nets formed by Ag⁺ ions. Perpendicular to these layers and along the c axis linear strings of Ag⁺ ions run through the large voids of the layers. Accordingly, Ag₅HgSbO₆ adopts the Ag₅Pb₂O₆ type of structure where the lead positions are occupied by mercury and antimony alternatingly. The finding of mercury in octahedral coordination, particularly besides the lower charged Ag⁺ cations in linear coordination, which is also highly preferred by Hg²⁺ ions, is rather unexpected. Ag₅HgSbO₆ starts to decompose at 450 °C and, in contrast to subvalent and metallic Ag₅Pb₂O₆, the new compound is charge balanced and semiconducting (ρ = 5.7 Ωcm at ambient temperature, E_a = 0.047 eV).     

Radical Arylation Reactions of 4, 6, 8-Trimethylazulene

The synthesis of 1- and 2-aryl-substituted (aryl = Ph, 4-NO₂? C₆H₄, and 4-MeO? C₆H₄) 4, 6, 8-trimethylazulenes ( 4 and 3 , respectively) in moderate yields by direct arylation of 4, 6, 8-trimethylazulene ( 8 ) with the corresponding arylhydrazines 13 in the presence of Cu^IIions in pyridine (see Scheme 4) as well as with 4-MeO? C₆H₄Pb(OAc)₃ ( 16 ) in CF₃COOH (see Scheme 5) is described. With 13 , also small amounts of 1, 2- and 1, 3-diarylated azulenes (see 14 and 15 , respectively, in Scheme 4) are formed. The 4-methoxyphenylation of 8 with 16 yielded also the 1, 1′-biazulene 17 in minor amounts (see Scheme 5). 4, 6, 8-Trimethyl-2-phenylazulene ( 3a ) was also obtained as the sole product in moderate yields by the reaction of sodium phenylclopentadienide ( 1a ) with 2, 4, 6-trimethylpyrylium tetrafluoroborate ( 2 ) in THF (Scheme 1). The attempted phenylation of 8 as well as of azulene ( 9 ) itself with N-nitroso-N-phenylacetamide ( 10 ) led only to the formation of the corresponding 1-(phenylazo)-substituted azulenes 12 and 11 , respectively (Scheme 3).     

Synthesis of 6-aryl-1,3-dimethyl-6,7-dihydro-6-azalumazin-7-(6H)ones and their conversion into 2-aryl-1,2,4-triazine-3,5-(2H,4H)odiones. A new synthesis of 1-aryl-6-azauracils

Treatment of 6-amino-5-arylazo-1,3-dimethyluracils with urea or N,N′-carbonyldiimidazole gave the respective 6-aryl-1,3-dimethyl-6,7-dihydro-6-azalumazin-7-(6H)ones, which were hydrolyzed with alkali to afford 2-aryl-2,3,4,5-tetrahydro-3,5-dioxo-1,2,4-triazine-6-carboxylic acids (1-aryl-6-azauracil-5-carboxylic acids). Thermal decomposition of these carboxylic acids gave the corresponding 2-aryl-1,2,4-triazine-3,5-(2H,4H)diones (1-aryl-6-azauracils). Methylation of the latter with methyl iodide gave the corresponding 2-aryl-4-methyl-1,2,4-triazine-3,5-(2H,4H)diones (1-aryl-3-methyl-6-azauracils).     

Reaction of 6-methyl-6-p-tolyl-4-ethoxy-5,6-dihydro-pyran-2-one1 with perchloric acid

6-Methyl-6-p-tolyl-4-ethoxy-5,6-dihydro-pyran-2-one (1) undergoes decarboxylative elimination with perchloric acid in ether to give 4-p-tolyl-3-penten-2-one (3), the structure of which has been confirmed through an unambiguous synthesis.

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Reaktion von 6-Methyl-6-p-tolyl-4-ethoxy-5, 6-dihydro-pyran-2-on mit PerchlorsäureKurze Mitteilung

Zusammenfassung Die Titelverbindung (1) ergibt mit Perchlorsäure unter decarboxylierender Eliminierung 4-p-Tolyl-3-penten-2-on (3). Die Struktur von3 wurde mittels eines eindeutigen Syntheseweges festgelegt.

     

Darstellung,Kristallstruktur, Schwingungsspektren und Normalkoordinatenanalyse von [Co(NH3)6][Os(SCN)6]

Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of [Co(NH₃)₆][Os(SCN)₆] From the mixture of the linkage isomers [Os(NCS)_n(SCN)_6–n]^3–, n = 0–2, pure [Os(SCN)₆]^3– has been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The X‐ray structure determination on a single crystal of [Co(NH₃)₆][Os(SCN)₆] (trigonal, space group R 3, a = 12.368(2), c = 11.830(2) Å, Z = 3) reveals that the thiocyanate ligands are exclusively S‐coordinated with the Os–S distance of 2.388 Å and the Os–S–C angle of 108.8°. The IR and Raman spectra of (n‐Bu₄N)₃[Os(SCN)₆] are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constant f_d(OsS) is 1.42 mdyn/Å.