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The synthesis of [Ph4As+]2[Cl4Re(NS)(NSCl)2-] · CH2Cl2 (4) from the reaction of S4N4, Cl4ReN, and Ph4AsCl is reported. CH2Cl2 is used as solvent. The reaction of S4N4 with Re2Cl10 similarly leads to the salt [Ph4As+][Cl2ReNS-] (5) in a smaller yield. 4 crystallizes in the triclinic space group P1̅ with Z = 2, a - 10.434(2), b = 12.1454(6), c = 21.125(2) Å, a = 81.210(6), β = 86.70(1), γ = 76.624(8)°.
The two-electron reduction of tetraphenyl-p-quinodimethane M via its radical anion M⊖ to its dianion M⊖⊖ is explored both by cyclovoltammetry and ESR/ENDOR spectroscopy. Contact of the diglyme solution with added 15-crown-5 under aprotic conditions with a sodium metal mirror yields black crystals of a solvent-separated contact ion triple [M⊖⊖][Na⊕(OCH2CH2)5(H3CO(CH2CH2O)2CH3)]2. The two-electron-insertion into the pquinodimethane derivative R2C⊖=C(HC=CH)2C=CR2 changes its structure drastically to that of a twofold carbanion substituted benzene, R2C⊖ -(C6H4)- ⊖CR2. MNDO calculations provide a rationale for both the tremendous solvation of a Na⊕ center coordinated to seven oxygen centers of 15-crown-5 and of one diglyme molecule and the structural changes as well as the charge distribution in the unique Tetraphenyl-p-quinodimethane dianion (H5C6)2C⊖-(C6H4)- ⊖C(C6H5)2, in which the two negative charges are largely localized at the carbanion center of the benzene -substituents.
The structures of seven di- or tetrasubstituted p-benzoquinone derivatives O=C(XC=CH )2C=O and O=C(XC=CX)2C=O with substituents X = -OCH3, -N(CH2)5, - N(CH2CH2)2O, -Cl, -CN and -⊕N(HC=CH)2C-N(CH3)2 are presented and discussed in comparison with published ones substituted by X = -Si(CH3)3, -C6H5, -N(CH3)2, -⊕N(HC=CH)2CN(CH3)2, -O⊖ , and - NO2. Based on the introduction, in which halfwave-reduction potentials, geometry-optimized quantum-chemical calculations on substituent perturbation and known structural data of p-benzoquinone derivatives are used to characterize their molecular ground states. The structural changes indicate how substituent perturbations might be rationalized. Of the categories defined - imperturbed, donor, donor/acceptor and acceptor perturbed - the donorsubstituted p-benzoquinones do exhibit the largest differences, often called cyanine distorsion. In very satisfactory agreement with extensive semiempirical calculations, all effects determined experimentally are discussed in terms of varying charge distribution. With respect to the biochemical importance of p-benzoquinone derivatives, this first structural summary points out important facets.
The following mixed-stack donor/acceptor complexes {D · · · A }∞ have been crystallized and their structures determined: { 1 ,2,4,5-tetramethylbenzene · · · tetrabromo-p -benzoquinone}∞ , {hexamethylbenzene · · · tetrabromo-p-benzoquinone}∞ , { ( 1 ,2 ,4,5-tetramethyl-benzene)2 · · · tetrachloro -p -benzoquinone}∞ , {pyrene · · · tetrafluoro-p-benzoquinone}∞ , {pyrene · · · tetrabromo-p-benzoquinone}∞ and {perylene · · · tetrabromo-p-benzoquinone}∞ . They exhibit an interesting lattice packing, especially the 2:1 tripeldecker sandwich of tetrachloro-p-benzoquinone, which crystallizes in a herringbone pattern. Their interplanar distances are around 340 pm, i. e. two van der Waals π radii. None of them , however, exhibits in neither the donor nor the acceptor components significant structural changes due to complex formation. Their colours range from orange-red to black in the crystal and to green in H2CCl2 solution. Their long-wavelengths charge transfer absorption maxim a correspond to a lowering in excitation energy of up to 2 eV relative to that of the components. The different charge transfer in the ground and excited states of the donor/acceptor complexes investigated is further discussed referring to data such as cyclovoltammetric reduction potentials as w ell as to results from semiempirical calculations based on the crystal structure data determined and including configuration interaction.
The compound [(PyH)3Br][AlBr4]2 is formed by melting stoichiometric amounts of AlBr/PyHBr in a ratio of 2:3. It crystallizes in the orthorhombic space group Pbca with lattice constants a = 1365.5(2), b = 1616.0(2), c = 2783.7(3) pm, Z = 8, Dc = 2.21 g/cm3. The structure was solved from 2810 diffractometer measured intensities (Cu -Kα radiation) and refined to Rw (F) = 0.071. The cation shows three pyridinium ions attached via N - H - Br hydrogen bonds to a central bromide ion. The N - Br distances are 321(1), 321(2) and 332(2) pm.
[Ph3PN(H)Ph][AuI2] (2) is formed by the reaction of AuI with N-Phenyl-iminotriphenylphosphorane, Ph3PNPh in a toluene suspension. 2,3-Bis(triphenylphosphinimino)maleic acid-N-methylimide (3) has been prepared by the Staudinger reaction of 2,3-bis(azido)maleic acid-N-methylimide with PPh3 in THF solution in the form of red crystals. Crystal structure determinations of three iminophosphoranes were carried out by X-ray methods.
Ph3PNPh (1): space group P21/c, Z = 4, 2176 independent observed reflexions, R = 0.057. Lattice dimensions (-30 °C): a = 1126.4, b = 1148.6, c = 1476.0 pm; β = 97.21°. The compound forms monomeric molecules with P=N = 160.2 pm and an PNC angle of 130.4°.
[Ph3PN(H)Ph][AuI2] (2): space group P1̄, Z = 2, 1780 independent observed reflexions, R = 0.057. Lattice dimensions (18 °C); a = 824.9, b = 1022, c = 1476.2 pm; α = 89.23°, β = 87.41°, γ = 85.65°. The compound consists of ions [Ph3PN(H)Ph]⊕ with P=N = 162.4 pm and PNC = 129.3°, and anions [AuI2]⊖ with Au-I = 261.9 and 259.3 pm, IAuI = 176.8°.
(Ph3P)2N2C4O2 (NMe) (3): space group P1̄, Z = 2, 4972 independent observed reflexions, R = 0.050. Lattice dimensions (-90 °C): a = 904.7, b = 993.8, c = 2017.4 pm; α = 101.55°, β = 96.39°, γ = 105.81°. The compound forms monomeric molecules with syn-conformation of the two NPPh3 groups. Bond lengths: P=N = 157.1; 155.3 pm, bond angles: PNC = 133°; 136°.
Host cell invasion by the facultative intracellular pathogen Listeria monocytogenes requires the invasion protein InlB in many cell types. InlB consists of an N-terminal internalin domain that binds the host cell receptor tyrosine kinase Met and C-terminal GW domains that bind to glycosaminoglycans (GAGs). Met binding and activation is required for host cell invasion, while the interaction between GW domains and GAGs enhances this effect. Soluble InlB elicits the same cellular phenotypes as the natural Met ligand hepatocyte growth factor/scatter factor (HGF/SF), e.g. cell scatter. So far, little is known about the central part of InlB, the B-repeat. Here we present a structural and functional characterization of the InlB B-repeat. The crystal structure reveals a variation of the β-grasp fold that is most similar to small ubiquitin-like modifiers (SUMOs). However, structural similarity also suggests a potential evolutionary relation to bacterial mucin-binding proteins. The B-repeat defines the prototype structure of a hitherto uncharacterized domain present in over a thousand bacterial proteins. Generally, this domain probably acts as a spacer or a receptor-binding domain in extracellular multi-domain proteins. In cellular assays the B-repeat acts synergistically with the internalin domain conferring to it the ability to stimulate cell motility. Thus, the B-repeat probably binds a further host cell receptor and thereby enhances signaling downstream of Met.
Triphenylmethylphosphonium nitrite and formate have been prepared by the reaction of [PPh3Me]I with silver nitrite, and lead formate, respectively, in aqueous solutions. [PPh3Me]NO2 (1) forms pale yellow crystals, and [PPh3Me]HCO2·H2O (2) forms white crystals. Both compounds are soluble in water, ethanol, and dichloromethane. In moist air 2 is hydrated to yield [PPh3Me]HCO2·2H2O (3). The compounds were characterized by their IR spectra, 1 and 2 also by X-ray crystal structure determinations.
[PPh3Me]NO2 (1): space group P21/n, Z = 4, 2088 independent observed reflexions, R = 0.062. Lattice dimensions (20 °C): a = 914.7(3), b = 1887.5(9), c = 1080.0(4) pm, β = 110.29(3)°. The compound consists of PPh3Me+ ions and NO2- anions with bond lengths of 114.2(6) pm and a bond angle of 124.1(7)°.
[PPh3Me]HCO2·H2O (2): space group P21/n, Z = 4, 2973 independent observed reflexions, R = 0.069. Lattice dimensions (-20 °C): a = 931(2), b = 1558(3), c = 1281(2) pm, β = 105.9(1)°. The compound consists of PPh3Me+ ions and formate anions which form centrosymmetric dimeric units [HCO2·H2O]22- through hydrogen bridges of the water molecules. Bond lengths CO 122.4(4) and 120.9(4) pm. bond angle OCO 129.9(4)°.
Cp2TiSe5 has been prepared by the reaction of trim ethyltetradecylammonium-polyselenide with Cp2TiCl2 in ethanol solution and subsequent extraction of the dry residue with dichloromethane. Cp2TiSe5 crystallizes in the space group P1 with two formula units in the unit cell (2559 observed, independent reflexions, R = 0.074). The cell dimensions are a = 808.6, b = 822.6, c = 1190.7 pm, α - 96.28°, β - 106.06°, γ = 108.78°. The structure consists of discrete Cp2TiSe5 molecules with the TiSe5, ring in the chair conformation.
The title compound has been prepared by the reaction of N-trimethylsilyl-iminotriphenylphos-phorane with copper(II) chloride in boiling CCl4 /C2H5OH, and forms moisture sensitive crystals, which are green in transmittance and black in reflexion. [Me3SiNPPh3 · CuCl2 ] 2 was characterized by its IR spectrum as well as by a crystal structure determination (4197 observed, independent reflexions, R = 0.049). The lattice dimensions are at 20 °C: a = 1102.7. b = 1407.3. c = 1560.2 pm; β = 94.27°; space group P21/n with two formula units in the unit cell. The complex consists of centrosymmetric, dimeric molecules with a planar Cu2 Cl2 ring (Cu-CI bond lengths 229 and 231 pm). A terminally bonded CI atom (Cu-CI = 221 pm) and the N atom of the Me3SiNPPh3 ligand (Cu-N = 198.5 pm) complete the coordination number four of the nearly planar surroundings of the Cu atoms.