Structures, Bonding Analyses and Reactivity of a Dicationic Digallene and Diindene Mimicking trans-bent Ditetrylenes

The reaction of bisdicyclohexylphosphinoethane (dcpe) and the subvalent MI sources [MI (PhF)2 ][pf] (M=Ga+ , In+ ; [pf]- =[Al(ORF )4 ]- ; RF =C(CF3 )3 ) yielded the salts [{M(dcpe)}2 ][pf]2 , containing the first dicationic, trans-bent digallene and diindene structures reported so far. The non-classical MI ⇆MI double bonds are surprisingly short and display a ditetrylene-like structure. The bonding situation was extensively analyzed by quantum chemical calculations, QTAIM (Quantum Theory of Atoms in Molecules) and EDA-NOCV (Energy Decomposition Analysis with the combination of Natural Orbitals for Chemical Valence) analyses and is compared to that in the isoelectronic and isostructural, but neutral digermenes and distannenes. The dissolved [{Ga(dcpe)}2 ]2+ ([pf]- )2 readily reacts with 1-hexene, cyclooctyne, diphenyldisulfide, diphenylphosphine and under mild conditions at room temperature. This reactivity is analyzed and rationalized.

Synthesis and Characterization of Stable Iron Pentacarbonyl Radical Cation Salts

The open‐shell iron pentacarbonyl cation [Fe(CO)₅]^.+ was isolated by deelectronation, i.e., the single‐electron oxidation of the parent neutral Fe(CO)₅ using [phenazine^F]^.+ as the [Al(OR^F)₄]⁻ and [F‐{Al(OR^F)₃}₂]⁻ salt (R^F=C(CF₃)₃; phenazine^F=perfluoro‐5,10‐bis(perfluorophenyl)‐5,10‐dihydrophenazine). [Fe(CO)₅]^.+[Al(OR^F)₄]⁻ was fully characterized (scXRD analysis, IR, NMR, EPR, ⁵⁷Fe spectroscopy, CV and SQUID magnetization study) and, apart from being a compound of fundamental interest, may serve as a precursor for low‐valent iron coordination chemistry.

The tin sulfates Sn(SO4)2 and Sn2(SO4)3: crystal structures, optical and thermal properties

We report the crystal structures of two tin(IV) sulfate polymorphs Sn(SO4)2-I (P2₁/c (no. 14), a = 504.34(3), b = 1065.43(6), c = 1065.47(6) pm, β = 91.991(2)°, 4617 independent reflections, 104 refined parameters, wR₂ = 0.096) and Sn(SO4)2-II (P2₁/n (no. 14), a = 753.90(3), b = 802.39(3), c = 914.47(3) pm, β = 92.496(2)°, 3970 independent reflections, 101 refined parameters, wR₂ = 0.033). Moreover, the first heterovalent tin sulfate Sn2(SO4)3 is reported which adopts space group P1̄ (no. 2) (a = 483.78(9), b = 809.9(2), c = 1210.7(2) pm, α = 89.007(7)°, β = 86.381(7)°, γ = 73.344(7)°, 1602 independent reflections, 152 refined parameters, wR₂ = 0.059). Finally, SnSO4 - the only tin sulfate with known crystal structure - was revised and information complemented. The optical and thermal properties of all tin sulfates are investigated by FTIR, UV-vis, luminescence and ¹¹⁹Sn Mössbauer spectroscopy as well as thermogravimetry and compared.

From 1D to 3D: Perovskites within the System HSC(NH2)2I/CH3NH3I/PbI2 with Maintenance of the Cubic Closest Packing

This work describes crystalline phases of the system [HSC(NH₂)₂]I/(CH₃NH₃)I/PbI₂ and discusses the crystal structures in the context of a common cubic closest packing of organic cations and iodide anions with Pb²⁺ in all anionic octahedral voids. Ternary boundary phases were (CH₃NH₃)PbI₃ (3D perovskite), [HSC(NH₂)₂]₃PbI₅ (1D perovskite), [HSC(NH₂)₂]PbI₃ (NH₄CdCl₃ type), and [HSC(NH₂)₂]Pb₂I₅, with strands of edge-sharing octahedra of the NH₄CdCl₃ type, which are connected to 2D layers via common corners. Within the system, we identified ribbonlike structures of the general composition [HSC(NH₂)₂]_m+1(CH₃NH₃)_mPb_mI_4m+1 with m = 2 and 3, representing the transition from 1D to 2D structures. Layered structures with variable thickness were found for the series [HSC(NH₂)₂](CH₃NH₃)_nPb_nI_3n+1 with n = 1-3. The color and band gap correlate directly with the pattern of how the PbI₆ octahedra are linked. 1D structures are colorless or pale yellow to orange. Layered structures are red to black, depending on the layer thickness. A first laboratory-scale solar cell yielded an efficiency of ∼6% based on the compound with n = 3.

Borosulfates-Synthesis and Structural Chemistry of Silicate Analogue Compounds

Borosulfates are oxoanionic compounds consisting of condensed sulfur- and boron-centered tetrahedra. Hitherto, they were mostly achieved from solvothermal syntheses in SO3 -enriched sulfuric acid, or from reactions with the superacid H[B(HSO4 )4 ]. The crystal structures are very similar to those of the corresponding class of silicates and their substitution variants, especially regarding the typical structural motif of corner-sharing tetrahedra. However, the borosulfates are supposed to be even more versatile, because (BO3 ) units might also be part of the anionic network. The following article deals with detailed reports on the different synthesis strategies, the crystal chemistry of borosulfates in comparison to silicates, and their hitherto identified properties.

Going Homoleptic: Synthesis and Full Characterization of Stable Manganese Tetranitrosyl Cation Salts

Although similar to carbon monoxide, the chemistry of homoleptic nitrogen monoxide complexes is fundamentally unexplored compared to their carbonyl analogues. Herein we report the synthesis of the first truly homoleptic transition-metal nitrosyl cation as the salt of the weakly coordinating anions (WCAs) [Al(OR^F )₄ ]^- and [F{Al(OR^F )₃ }₂ ]^- (R^F =C(CF₃ )₃ ). These salts are easily accessible in good yields, phase pure, and were fully characterized by IR/Raman, NMR and UV/Vis spectroscopy as well as single-crystal and powder X-ray diffraction. They may serve as unprecedented simple model systems for theoretical and experimental studies of nitrosyl complexes.

Stable salts of the hexacarbonyl chromium(I) cation and its pentacarbonyl-nitrosyl chromium(I) analogue

Homoleptic carbonyl radical cations are a textbook family of complexes hitherto unknown in the condensed phase, leaving their properties and applications fundamentally unexplored. Here we report on two stable 17-electron [Cr(CO)6]•+ salts that were synthesized by oxidation of Cr(CO)6 with [NO]+[Al(ORF)4]- (RF = C(CF3)3)) in CH2Cl2 and with removal of NO gas. Longer reaction times led to NO/CO ligand exchange and formation of the thermodynamically more stable 18-electron species [Cr(CO)5(NO)]+, which belongs to the family of heteroleptic chromium carbonyl/nitrosyl cations. All salts were fully characterized (IR, Raman, EPR, NMR, scXRD, pXRD, magnetics) and are stable at room temperature under inert conditions over months. The facile synthesis of these species enables the thorough investigation of their properties and applications to a broad scientific community.

First representatives of (210)-oriented perovskite variants−Synthesis, crystal structures and properties of the new 2D hybrid perovskites A[HC(NH2)2]PbI4; A=[C(NH2)3], [HSC(NH2)2]

Single crystals of [C(NH2)3][HC(NH2)2]PbI4 (GuFAPbI4) and [HSC(NH2)2][HC(NH2)2]PbI4 (TuFAPbI4) were obtained from solutions of the binary halides in HI or DMF. Large crystals grown from HI are dark-brown while single phase powders synthesized from DMF are orange. The crystal structure of GuFAPbI4 (I2/m, Z=12, a=14.3147(2), b=12.7591(2), c=25.7377(4)Å), β=101.459(1), 4256 refl., 196 param., R1=0.024, wR2=0.061) represents a 2D perovskite with a new motif similar to Ruddlesden-Popper phases (AX)m(A′BX3)n and m=n=1. The layers are formed by corner-sharing PbI6 octahedra. According to the cut-out of the 3-D perovskite the structure of GuFAPbI4 can be assigned as a (210)-oriented representative. So one octahedron is linked in trans-position and two in cis-orientation. The structure of TuFAPbI4 (P21/n, Z=12, a=14.4208(6), b=12.7545(7), c=26.3982(11) Å), β=100.609(3)°, 6808 refl., 275 param., R1=0.048, wR2=0.096) represents a simple distortion variant of GuFAPbI4. GuFAPbI4 and TuFAPbI4 were further characterized by vibrational spectroscopy and optical spectroscopy. The optical band gap was determined as 2.34 eV in agreement to the observed color. So both compounds are not suitable as a dye in the PSC perovskite solar cell. Similar to other Pb-containing 2D perovskites there is a significant excitonic peak (2.31 eV). TuFAPbI4 represents the first example with protonated thiourea as an organic cation. Therefore, we characterized protonated thiourea iodide and introduce protonated thiourea [HSC(NH2)2]+ as a new cation for hybrid halogeno perovskites.

Tailoring the Band Gap in 3D Hybrid Perovskites by Substitution of the Organic Cations: (CH3 NH3 )1-2y (NH3 (CH2 )2 NH3 )2y Pb1-y I3 (0≤y≤0.25)

Tuning the optical properties of MAPbI₃ (MA=methylammonium) is a key requirement to increase the efficiency of perovskite solar cells (PSCs). Simple precipitation from solution allows the partial substitution of MA in MAPbI₃ by H₃ NCH₂ CH₂ NH₃ (H₂ en). Surprisingly, there is 1:1 exchange of the monovalent cation MA by the dication H₂ en. The charge compensation results from a deficit of Pb²⁺ , leading to a series MA_1-2y (H₂ en)_2y Pb_1-y I₃ with 0≤y≤0.25. This model has been supported by single-crystal measurements and NMR investigations. The substitution results in a continuous shift of the band gap from 1.51 to 2.1 eV and a color change from black to orange-red. The H₂ en content stabilizes the cubic high-temperature (HT) form of MAPbI₃ . There is a linear correlation between band gap and unit cell volume. The substitution enables controlled band gap tuning because the extent of substitution is closely related to the applied MA:H₂ en ratio in solution.

Synthesis, Crystal Structure, and Properties of Bi3 TeBO9 or Bi3 (TeO6 )(BO3 ): A Non-Centrosymmetric Borate-Tellurate(VI) of Bismuth

Pale-yellow single crystals of the new borate tellurate(VI) Bi₃ TeBO₉ were obtained by reaction of stoichiometric amounts of Bi₂ O₃ , B₂ O₃ , and Te(OH)₆ at 780 °C. The non-centrosymmetric crystal structure (P6₃ , Z=2, a=8.7454(16), c=5.8911(11) Å, 738 refl., 43 param, R1=0.037, wR2=0.093) contains isolated trigonal-planar BO₃ units and nearly undistorted TeO₆ octahedra. The Bi³⁺ cations are located in between in octahedral voids. The BiO₆ octahedra are significantly distorted to a [3+3] pattern (2.25/2.50 Å) due to the ns² configuration. According to the structural features, the formula can be written as Bi₃ (TeO₆ )(BO₃ ). Alternatively, the structure can also be described as hcp of oxygen with Te^VI and Bi^III in octahedral voids and B^III in trigonal- planar voids. The vibrational spectra show the typical features of BO₃ and TeO₆ units with a significant ¹⁰ B/¹¹ B isotopic splitting of the IR-active B-O valence mode (1248 and 1282 cm^-1 ). The UV/Vis spectrum shows an optical band edge with an onset around 480 nm (2.6 eV). MAS-NMR spectra of ¹¹ B show an anisotropic signal with a quadrupole coupling constant of C_Q =2.55 MHz. and a very small deviation from rotational symmetry (η=0.2). The isotropic chemical shift is 20.1 ppm. The second harmonic generation (SHG) test was positive with an activity comparable to potassium dihydrogen phosphate (KDP). Bi₃ TeBO₉ decomposes in air at 825 °C to Bi₂ TeO₅ .

Synthesis, single-crystal structure and characterization of (CH3 NH3 )2 Pb(SCN)2 I2

The perovskite phase (CH3 NH3 )2 Pb(SCN)2 I2 with a structure closely related to the K2 NiF4 -type was identified as the product of the reaction of CH3 NH3 I and Pb(SCN)2 by single-crystal X-ray analysis. This extends the range of suitable dyes for solar cell applications to a class of perovskite-related structures of the general composition (AMX3 )n (AX)m .

Mathematical Model Creation for Cancer Chemo-Immunotherapy

One of the most challenging tasks in constructing a mathematical model of cancer treatment is the calculation of biological parameters from empirical data. This task becomes increasingly difficult if a model involves several cell populations and treatment modalities. A sophisticated model constructed by de Pilliset al.,Mixed immunotherapy and chemotherapy of tumours: Modelling, applications and biological interpretations, J. Theor. Biol. 238 (2006), pp. 841–862; involves tumour cells, specific and non-specific immune cells (natural killer (NK) cells, CD8+T cells and other lymphocytes) and employs chemotherapy and two types of immunotherapy (IL-2 supplementation and CD8+T-cell infusion) as treatment modalities. Despite the overall success of the aforementioned model, the problem of illustrating the effects of IL-2 on a growing tumour remains open. In this paper, we update the model of de Pilliset al.and then carefully identify appropriate values for the parameters of the new model according to recent empirical data. We determine new NK and tumour antigen-activated CD8+T-cell count equilibrium values; we complete IL-2 dynamics; and we modify the model in de Pilliset al.to allow for endogenous IL-2 production, IL-2-stimulated NK cell proliferation and IL-2-dependent CD8+T-cell self-regulations. Finally, we show that the potential patient-specific efficacy of immunotherapy may be dependent on experimentally determinable parameters.

Uterine and fetal findings at hysteroscopic evaluation of spontaneous abortions before D&C

STUDY OBJECTIVE

To evaluate the diagnostic benefit of fluid hysteroscopy before dilatation and curettage (D&C) in women with missed abortion, with respect to frequency of congenital and acquired uterine anomalies and geographic relationship of uterine anomalies to nidation site.

DESIGN

Prospective case study (Canadian Task Force classification II-2).

SETTING

Obstetric-gynecologic clinic of an academic teaching hospital.

PATIENTS

One hundred five women with one or more recurrent missed abortions.

INTERVENTION

Hysteroscopy before D&C. Inspection of the fetus was attempted in 62 patients. Control hysteroscopy of the nonpregnant uterus was performed in 20 patients.

MEASUREMENTS AND MAIN RESULTS

The uterine cavity was visualized in 87 patients (83%). These women had an obstetric history significant for 143 spontaneous abortions in 208 pregnancies. Except for three small, finger-shaped polyps in the tubal ostia, no uterine anomalies were detected. In 20 women control hysteroscopy of the nonpregnant uterus confirmed initial findings. The fetus was successfully visualized in 30 cases (48%). We observed one case of umbilical cord torsion at 12 weeks' gestation.

CONCLUSION

Absence of uterine anomalies in patients with single as well as recurrent spontaneous abortions was unexpected since it contradicts the existing literature. However, all previous data were gathered from hysteroscopies of nonpregnant uteri. Larger comparative studies are required.

A new model for in vitro clot formation that considers the mode of the fibrin(ogen) contacts to platelets and the arrangement of the platelet cytoskeleton

The constitution of platelet-fibrin(ogen) contacts, the separation of the platelets initially aggregated, and the rearrangement of the platelet cytoskeleton during clot formation (0.5 to 60 minutes after thrombin stimulation) were investigated using ultrastructural and immunocytochemical techniques. After aggregation, fibrin polymerizing within focal contacts and from degranulating secretory granules contributed to the fibers. The initially formed focal contacts with fibrin obviously persisted during clot formation. The physiological branching of the fibers enabled separation of platelets. The contact associated cytoskeleton formed a constricting and fiber internalizing sphere, but later stress fiber like bundles. As retraction progressed, the cytoskeleton changed to stress fiber connecting focal contacts with fibers. A model of clot formation in vitro is presented that reflects both the contributions of platelets (fibrin fiber internalization and retraction) and of fibers (branching) enabling the retraction.

The RafC1 cysteine-rich domain contains multiple distinct regulatory epitopes which control Ras-dependent Raf activation

Activation of c-Raf-1 (referred to as Raf) by Ras is a pivotal step in mitogenic signaling. Raf activation is initiated by binding of Ras to the regulatory N terminus of Raf. While Ras binding to residues 51 to 131 is well understood, the role of the RafC1 cysteine-rich domain comprising residues 139 to 184 has remained elusive. To resolve the function of the RafC1 domain, we have performed an exhaustive surface scanning mutagenesis. In our study, we defined a high-resolution map of multiple distinct functional epitopes within RafC1 that are required for both negative control of the kinase and the positive function of the protein. Activating mutations in three different epitopes enhanced Ras-dependent Raf activation, while only some of these mutations markedly increased Raf basal activity. One contiguous inhibitory epitope consisting of S177, T182, and M183 clearly contributed to Ras-Raf binding energy and represents the putative Ras binding site of the RafC1 domain. The effects of all RafC1 mutations on Ras binding and Raf activation were independent of Ras lipid modification. The inhibitory mutation L160A is localized to a position analogous to the phorbol ester binding site in the protein kinase C C1 domain, suggesting a function in cofactor binding. Complete inhibition of Ras-dependent Raf activation was achieved by combining mutations K144A and L160A, which clearly demonstrates an absolute requirement for correct RafC1 function in Ras-dependent Raf activation.