Showing papers by "George M. Sheldrick published in 1982"

Cyclo-octasulphur as a ligand; preparation and X-ray crystal structure of [Ag(S8)2]AsF6

Abstract: Reaction of AgAsF6 with S8 in liquid sulphur dioxide leads to [Ag(S8)2]AsF6, which contains cyclo-octasulphur ligands; the X-ray structure shows that the silver atoms achive distorted four-co-ordination by 1,3-linkages to two S8 rings.

Kristallstrukturen der selenid- bzw. sulfidverbrückten Gold(I)verbindungen [Se(AuPPh3)+3]PF6- und [S(AuPPh3)2] · CH2Cl2/Crystal Structures of the Selenide- and Sulphide-Bridged Gold(I) Complexes [Se(AuPPh3)3]+PF6- and [S(AuPPh3)2] · CH2Cl2

Abstract: Abstract The Compound [S(AUPPh3)2] · CH2Cl2 was prepared from Ph3PAuCl and H2S in CH2Cl2 and characterised by X-ray structure determination [P21/c, a = 1851.6(4), b = 2225.1(6), c = 880.3(2) pm, β = 96.32(1)°, Z = 4, R = 0.053]. A constrained refinement of the light atom positions was necessary because of pseudosymmetry. Ph3PAuPF6 reacts with Se(Sn)(CH3)3)2 to give [Se(AuPPh3)3]+PF6- which was also characterised by X-ray methods [P1̄, a = 1539.5(6), b = 1800.5(7), c = 2289.5(9) pm, α = 89.35(3), β = 72.44(3), γ = 69.75(3)°, Z = 4, R = 0.061]. There are two formula units in the asymmetric unit. Both structures show short Au···Au contacts (ca. 300-340 pm).

Tris(pentafluorophenyl)gold(III) complexes

Abstract: The preparation of [Au(C6F5)3(tht)](tht = tetrahydrothiophen) by oxidation of [Au(C6F5)(tht)] with [Tl(C6F5)2Cl] is described. Displacement of tht by other neutral or anionic unidentate ligands leads to the synthesis of [Au(C6F5)3L][L = NH3, py, PMePh2, P(OPh)3, AsPh3, SbPh3 or CNC6H4Me-p] or Q[Au(C6F5)3X][Q = NEt4, NBu4, PPh3(CH2Ph), or N(PPh3)2; X = Cl, I, SCN, or N3]. The compound [Au(C6H5)3(CNC6H4Me-p)] adds amines to give the gold(III)–carbene complexes [Au(C6F5)3{C(NHC6H4Me-p)(NR2)}](NR2= NHC6H4Me-p, NEt2, or NHCH2CH2NH2). The reaction of the compound [Au(C6F5)3(tht)] with potentially bidentate ligands takes two different courses. (a)o-Phenylenebis(dimethylarsine)(pdma) and 1,2-bis(diphenylphosphino)methane (dppm) give four-co-ordinated complexes, in which the ligands are unidentate; the pdma complex has inequivalent methyl hydrogens at low temperature (1H n.m.r.) and the dppm complex inequivalent P atoms (31P n.m.r.). An X-ray structure of the pdma complex confirms four-co-ordination in the solid state; space group P21/n, a= 10.796(3), b= 17.347(6), c= 16.275(5)A, β= 94.47(3)°, Z= 4, R= 0.058 for 3 357 reflections. (b) 1,2-Bis(diphenylphosphino)ethane (dppe) acts as a bridging ligand leading to the formation of [(C6F5)3Au(µ-dppe)Au(C6F5)3]. Similar reactions starting from [Au(C6F5)(2,4,6-C6F3H2)2(tht)] lead to the compounds [Au(C6F5)(2,4,6-C6F3H2)2(PPh3)] or [NBu4][Au(C6F5)(2,4,6-C6F3H2)2Br]. The arylation of [Au(C6F5)3Cl]– or [Au(C6F5)(2,4,6-C6F3H2)2Br]– with Ag(C6F5) leads to [Au(C6F5)4]– and [Au(C6F5)2(2,4,6-C6F3H2)2]– respectively.

Synthese und Struktur von [CpFe(CO)2SO2]+ AsF6- / Synthesis and Structure of [CpFe(CO)2SO2]+ AsF6–

Abstract: Abstract The cationic sulfur dioxide complexes [CpFe(CO)2SO2]+AsF6- (7) and [CpCr(NO)2SO2]+AsF6- (9) are obtained in almost quantitative yield from CpFe(CO)2I(CpCr(NO)2Cl) and AgAsF6 in liquid SO2. With excess transition metal halide dinuclear halogen-bridged cations ([CpFe(CO)2IFe(CO)2Cp]+ and [CpCr(NO)2ClCr(NO)2Cp]+) are formed. The crystal structure of 7 is reported, and the bonding in the complexes is discussed in the light of spectroscopic data.

2-Ethyl-5-(3-indolyl)oxazole from Streptomyces cinnamomeus discovered by chemical screening. Characterization and structure elucidation by X-ray analysis.

Abstract: In the lipophilic extracts from Streptomyces cinnamomeus 2-ethyl-5-(3-indolyl)oxazole (1a) was detected by chemical screening methods. The structure of the crystalline 1a was determined by spectroscopic and X-ray analysis. The new mono- and dibromo derivatives 1b and 1c are described. 1a is identical with pimprinethine and belongs to a group of microbial indole alkaloids, which can be regarded as masked tryptamine derivatives.

MeNC Insertion into Pd–C6F5 bonds: bis(µ-imidoyl-C,N)palladium complexes, a novel type of imidoyl co-ordination in palladium chemistry. Single-crystal X-ray structure of [Pd2{µ-C(C6F5)N(Me)}2Cl2(SC4H8)2]

Abstract: The complex cis- or trans-[Pd(C6F5)2(CNMe)2] reacts with PdCl2 or [PdCl2(NCPh)2] to give [Pd2(µ-Cl)2(C6F5)2(CNMe)2] which in turn undergoes MeNC insertion to give cis-[{Pd2(µ-Cl)2[µ-C(C6F5)N(Me)]2}n]. The latter undergoes cleavage of the chloro-bridges by neutral ligands [L = CNMe, NMe3, py, 4Me-py, 4But-py (py = pyridine), PPh3, and SC4H8] affording dimeric complexes [LCl[graphic omitted]dClL]. {For L = CNMe the complex can also be obtained by heating trans-[Pd(C6F5)Cl(CNMe)2].} The polymer also reacts with Tl(acac)(acac = acetylacetonate) or Ag(O2CMe) affording the corresponding imidoyl-bridged dimers. The 1H n.m.r. spectra show a mixture of two isomers for L = py, 4Me-py, and 4But-py; the four 19F n.m.r. spectra recorded reveal restricted rotation for the C6F5 group. The bridging location of the imidoyl groups has been ascertained by a single-crystal X-ray structure determination of the complex with L = SC4H8(tetrahydrothiophen), which crystallizes in the monoclinic space group P21/c, with unit-cell dimensions a= 9.304(2), b= 9.563(2), c= 34.979(5)A, β= 95.76(2)°, and Z= 4. The structure was solved by the heavy-atom method and refined to R= 0.040 for 3 978 observed reflections.

Preparation and crystal structure of the four-co-ordinate gold(I) complex chlorotris(triphenylphosphine)gold(I)

Abstract: The reaction between stoicheiometric amounts of triphenylphosphine and chloro(triphenylphosphine)-gold(I) in acetonitrile leads to chlorotris(triphenylphosphine)gold(I). An X-ray structure determination [space group P21/n, a= 10.197(2), b= 33.586(6), c= 13.306(2)A, β= 90.04(2)°, Z= 4, R′= 0.047 for 6 272 reflections] shows the presence of four-co-ordinate gold(I) with a long Au–Cl bond (2.710 A). Related thermochemical and 31P n.m.r. data are presented.

Formation of Metal-Metal Bonds and Conversion of the Metal Aggregate {Mo4(S2)4(S′2)2} by Atom-Transfer and Redox Reactions at Nonequivalent Ligands; [Mo4S4(NO)4(CN)8]8− an Anion with a Central Cubane-Like Unit†

Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1177. DOI:10.1002/anie.198211770

Schwefel‐Anionen mit der Koordinationszahl 3: Synthese, Struktur und Existenzbereich

Abstract: Die Umsetzungen von Sulfonylschwefeldiimiden mit Alkalialkoholaten fuhren zu den Salzen 1a–g. Eine Rontgenstrukturanalyse von 1f zeigt die erwartete Geometrie mit dem zentralen dreifach koordinierten Schwefelatom. 1c reagiert mit elementarem Chlor zum Natriumsalz 2 der azaanalogen Chlorsulfonsaure. Setzt man NaNH2 als Nucleophil mit Bis(phenylsulfonyl)schwefeldiimid um, so entsteht als Hauptprodukt Tris(phenylsulfonylimido)sulfit (3), dessen Struktur ebenfalls durch eine Rontgenstrukturanalyse aufgeklart wurde. Analog dem SO-Anion besitzt in 3 das zentrale Schwefelatom trigonal pyramidale Konfiguration. Die azaanaloge Verbindung 4 der Fluorsulfinsaure entsteht bei der Reaktion von Bis(phenylsulfonyl)schwefeldiimid mit sorgfaltig getrocknetem CsF. Bei der Umsetzung von Bis(trimethylsilyl)schwefeldiimid mit CsF, das etwa 7% Wasser enthalt, bildet sich das monomere Caesiumsalz des Sulfimids, das nach Kationenaustausch in Form der Salze 5a und b charakterisiert wurde. Tetraphenylphosphoniummethoxid reagiert mit 5-(Trimethylsilyloxy)-1,3λ4,2,4,6-dithiatriazin-1,1-dioxid (6) unter CH3OSi(CH3)3-Abspaltung zu 7. Das Anion von 7 enthalt eine Carbonylgruppe. Anions of Sulfur with the Coordination Number 3: Synthesis, Structure, and Range of Existence Sulfonylsulfur diimides react with alkali alcoxides to form the salts 1a–g. An X-ray structural analysis of 1f shows the expected geometry with the central threefold coordinated sulfur atom. 1c reacts with elemental chlorine to yield the sodium salt 2, the aza analogue of chlorosulfonic acid. When NaNH2 is used as a nucleophile for the reaction with bis(phenylsulfonyl)sulfur diimide, tris(phenylsulfonylimido)sulfite (3) is formed as the main product. Also the structure of 3 was elucidated by means of an X-ray analysis. Analogous to the SO-anion, 3 has a central sulfur atom with trigonal pyramidal configuration. The analogous aza compound of the fluorosulfinic acid 4 is formed by the reaction of bis(phenylsulfonyl)sulfur diimide with carefully dried CsF. By the reaction of bis(trimethylsilyl)sulfur diimide with CsF, which contains about 7% of water, the monomeric cesium salt of sulfonimide is formed. The salts 5a und b were obtained by cation exchange of the cesium salt. Tetraphenylphosphonium methoxide reacts with 5-(trimethylsilyloxy)-1,3λ4,2,4,6-dithiatriazin 1,1-dioxide (6) by elimination of CH3OSi(CH3)3 to yield 7. The anion of 7 contains one carbonyl group.

Knüpfung von Metall‐Metall‐Bindungen und Umwandlung des Metall‐Aggregats {Mo4(S2)4(S 2′)2} durch Atom‐Transfer‐ sowie Redox‐Reaktionen an nichtäquivalenten Liganden; über [Mo4S4(NO)4(CN)8]8− mit zentraler cubanartiger Einheit

Abstract: Das vollstandige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1982, 1177. DOI: 10.1002/ange.198211770

Kristallstruktur der sulfidverbrückten Gold(I)verbindung [Au{S(AuPPh3)2}2]+ [(CH3)3SnCl2]— / Crystal Structure of the Sulphide-bridged Gold(I) Complex [Au{S(AuPPh3)2}2]+[(CH3)3SnCl2]–

Abstract: The compound [Au{S(AuPPh3)2}2]+[(CH3)3SnCl2]- was prepared by the reaction of Ph3PAuCl with ((CH3)3Sn)2S and characterised by an X-ray structure determination [C2/c, a = 1713.4(5), b = 2996.7(12), c = 3081.7(12) pm, β = 102.40(3)°, Z = 8, R = 0.074]. The cation displays short Au ··· Au contacts and narrow Au-S-Au angles ( < 90°). The chlorine atoms of the anion are axially arranged. There are two independent anions, one lying on, and the other disordered about, the crystallographic twofold axes

Crystal and molecular structure of the quinoxaline antibiotic analog TANDEM (des-N-tetramethyltriostin A)

Abstract: The crystal structure of TANDEM (des-N-tetramethyltriostin A), a synthetic analogue of the quinoxaline antibiotic triostin A, has been determined independently at -135 and 7 'C and refined to R values of 0.088 and 0.147, respectively. The molecule has approximate 2-fold symmetry, with the quinoxaline chromophores and the disulfide cross-bridge projecting from opposite sides of the peptide ring. The quinoxaline groups are nearly parallel to each other and separated by about 6.5 A. The peptide backbone resembles a distorted antiparallel 13 ribbon joined by intramolecular hydrogen bonds N-H(LVal)--O(L-Ala). At low temperatures, the TANDEM molecule is surrounded by a regular first- and second-order hydration sphere containing 14 independent water molecules. At room temperature, only the first-order hydration shell is maintained. Calculations of the interplanar separation of the quinoxaline groups as a function of their orientation with respect to the peptide ring support the viability of TANDEM to intercalate bifunctionally into DNA.

S6N5O4, eine Verbindung mit cyclischem Radikalkation S3N 2+ und cyclischem Anion S3N3O 4− in getrennten Stapeln

Abstract: Das vollstandige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1982, 1273. DOI: 10.1002/ange.198212730

The crystal structure of 2-(4-chlorophenoxy)-tetrahydropyran

Abstract: The crystal structure of the title compound has been determined (space group Ρ J, a = 6.774(3), b = 8.900(4), c = 9.811(4) Α, α = 66.06(2), /3 = 86.67(3), y = 76.87(2)°, Ζ = 2) and refined to R = 0.040. The bond lengths at the acetal centre are consistent with a previously published bond· length/reactivity correlation (Jones and Kirby, 1979). Introduction We have shown recently (Jones and Kirby, 1979) that there is a linear correlation between reactivity and the length of the exocyclic C — Ο bond in a series of three 2-aryloxy-tetrahydropyran acetals. To test the strength of this correlation we have prepared several more acetals in this series, and report here the crystal and molecular structure of one of the simplest such compounds to exist in crystalline form at room temperature, the 4-chlorophenoxy acetal (1). (1) was prepared by the acid-catalysed addition of p-chlorophenol to dihydropyran. The phenol (0.025 mol) and dihydropyran (0.05 mol) were dissolved in dry ether and a few crystals of p-toluenesulphonic acid added. After stirring for 3 h under nitrogen, the solution was allowed to stand 1 Crystal Structures of Acetals, Part 6. Parts 1—5 are the first five references 2 All correspondence to P.G.J, (above address) 266 P. G. Jones et al.: The crystal structure of 2-(4'-chlorophenoxy)-tetrahydropyrran Table 1. Atom coordinates ( χ 10) and temperature factors (Α χ 10 ). The anisotropic termperature factor has the form 7~= — 2π {£/,, h a* + . . . 2 Vi2 hka*b* + ... J

X-Ray crystal structure of bis(1-oxo-1λ4,2,4λ4,3,5-trithiadiazole)silver hexafluoroarsenate(V); an unusual mode of co-ordination

Abstract: Ag+ and S3N2O form a 1 : 2 complex; X-ray crystal structure of the As F6– salt shows linear co-ordination of Ag by the ring N atoms, with more distant O and F completing an octahedron.

Cyclisierungsreaktionen lithiierter Fluorsilanole und Aminofluorsiloxane - Kreuzdimerisierung eines Silicenium-Ylids / Cyclisation Reactions of Lithiated Fluorosilanols and Aminofluorosiloxanes - Cross-dimerisation of a Silicenium-Ylid

Abstract: KOH reacts with bis(isopropyl-trimethylsilyl)-amino-difluorosilane to give the fluoro-silanol 1. An aminofluorosiloxane 2 is obtained in the reaction of [(Me3Si)2N]2SiF2 with KOH via a 1,3-silyl-group migration. The four-membered SiOSiN ring 5 can be prepared in several steps from 1. Six-membered SiO rings 8-10 are formed in the reaction of 1,3-fluorosilanols 6 and 7 with butyllithium. Lithiated 2 reacts with PCl3 to give a four-membered P2N2 ring 11, and with 2-methyl-2-propenal to give two isomeric (2 + 4) cycloadducts 12 and 13. The silicenium ylid formed initially by thermal elimation of LiF from lithiated 2 in PE/THF cross-dimerises to give a Si2N2 ring 14. If the reaction is carried out in n-heptane, the product after recrystallisation from acetone, 16, is an isomer of 14. The crystal structures of 14 and 16 have been determined.

S6N5O4, A Compound with Separately Stacked Cyclic Radical Cations S3N 2+ and Cyclic Anions S3N3O 4−

Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1273. DOI:10.1002/anie.198212730

Synthesis and Structure of Triply Coordinated Sulfur Anions

Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 269. DOI:10.1002/anie.198202690

Synthesis and Structure of [Zn(S2N2CO)6][AsF6]2—Sulfur‐Nitrogen Rings as Ligands in Coordination Compounds

Abstract: [21 I (259 mg, 1.06 mmol) was hydrogenated in 10 mL anhydrous DMF with 201 mg 10% Pd/C (3 h). The catalyst was filtered off and removal of the solvent gave 225 mg crude material, chromatography of which on 7 g silica gel (Kieselgel60) afforded 97 mg (43.0%) 2, m.p.= 137.5-138.5 "C (nhexane). Elution with n-hexane/ethyl acetate (1 : l), and n-hexane/ethyl acetate (I : 1/1 :2) gave 84 mg of the eluate, which after preparative thin layer chromatography on silica gel (CH2CI2/acetone 1 : 1) yielded 31 mg (12.7%) 3, m.p.=104.5-106.O"C (benzene) 131, 13 mg (5.7%) 4, m.p. 262.5-264.O"C (acetone) [3] and 34 mg (17.2%) 5, m.p.=78.0-79.0 "C (nhexane).

The crystal structure of l,2,3,4,6-penta-0-acetyl-β-D-glucopyranose

Abstract: The crystal structure of the title compound (1) has been determined [space group P2X2¿X, a = 5.747(3), b = 14.182(5), c = 24.480(5) Â, Ζ = 4] and refined to R 0.087 for 2059 unique observed reflections. The limited accuracy (typical bond length e.s.d.'s 0.008 A) is associated with a disordered acetyl group at C(6). The endocyclic acetal bond is longer than the exocyclic by 0.018 Â, reversing the pattern observed in the α-isomer (preceding paper).