Amorphous Alloys Atomic Structure Investigation by Means of Electron Microscopy and Diffraction

In the paper, the atomic structure of amorphous and nanocrystalline alloys of the electrolytically obtained CoP, NiP, CoNiP, CoW, and CoNiW systems has been studied. The structure was investigated by electron microscopy and diffraction using a Libra 200 HR FE transmission electron microscope at an accelerating voltage of 200 kV within a temperature range of 50-35 °C. The obtained radial atom distribution function and the coordination sphere radii are in good agreement with the data for the cobalt structure in the cubic and hexagonal modifications. The high coordination numbers of the third and fourth coordination spheres allow suggesting a predominantly cubic structure of the local atom environment in CoP samples but somewhat lower, which is explained by the presence of free volume and phosphorus atoms distorting the local structure. When heating, the near atomic order also corresponds to the cubic phase of cobalt, and the ordering occurs in the second, third, and fourth coordination spheres. The data obtained for CoNiP alloys indicate that by configuration, the local atomic environment is closer to the hexagonal structure of nickel. In general, the structure of the CoP-CoNiP system alloy films obtained by electrolytic deposition is already in one of the local minima of the total system energy, which is confirmed by the near atomic order similar to the cubic phase of cobalt or hexagonal phase of nickel. This determines the good stability of the structure and properties during thermal exposure.

Structural study of Pt(II) and Pd(II) complexes with quinoline-2-carboxaldehyde thiosemicarbazone

Two square-planar complexes, [PtLCl] (1) and [PdLCl] (2), were synthesized with quinoline-2-carboxaldehyde thiosemicarbazone ligand (HL), and characterized by IR and NMR spectroscopy and single crystal X-ray diffraction analysis. In both complexes L? is coordinated tridentately via the same donor atom set, while the fourth coordination site is occupied by chloride ion. However, the complexes are not isostructural due to different types of non-covalent intermolecular interactions. These interactions were analyzed using Hirshfeld surfaces and two-dimensional fingerprint plots.

How does the mood stabilizer lithium bind ATP, the energy currency of the cell

Lithium, in the form of a salt, is a mood stabilizer and a leading drug for the treatment of bipolar disorder. It has a very narrow therapeutic range and a variety of side effects. Lithium can replace magnesium and other cations in enzymes and small molecules, among them ATP, thereby affecting and inhibiting many biochemical pathways. The form of binding of lithium ions to ATP is not known.Here we extract the binding environment of lithium in solid ATP using a multi-nuclear multi-dimensional solid-state NMR approach.We determine that the coordination sphere of lithium includes, at a distance of 3.0(±0.4) Å, three phosphates; the two phosphates closest to the ribose ring from one ATP molecule, and the middle phosphate from another ATP molecule. A water molecule most probably completes the fourth coordination. Despite the use of excess lithium in the preparations, sodium ions still remain bound to the sample, at distances of 4.3-5.5 Å from Li, and coordinate the first phosphate and two terminal phosphates.In conclusion, solid-state NMR enables to unravel the exact coordination of lithium in ATP showing binding to three phosphates from two molecules, none of which are the terminal gamma phosphate. The methods we use are applicable to study lithium bound to a variety of ATP-bound enzymes, or to other cellular targets of lithium, consequently suggesting a molecular basis for its mode of action.

Cyclometallated tridentate platinum(ii) arylacetylide complexes: old wine in new bottles

Platinum(ii) cyclometallated pincer complexes with an alkynyl ligand in the fourth coordination site display excellent luminescent properties. By manipulation of the pincer and the alkynyl ligand their luminescence can be fine-tuned for opto-electronic applications.

Ligand-modulated ring-expansion

An unstrained metal-containing macrocycle was ring-expanded by a ring-opening metathesis strategy, leading to the formation of a bimetallic dimeric macrocycle. The reaction is driven by coordination of a bulky ligand, 2,6-lutidine, on the fourth coordination site of the palladium center. In the absence of metal, or with a less bulky ligand, the ring-expansion reaction does not proceed.

Synthesis and structure of an aryltellurenium(II) cation; [4-tert-butyl-2,6-bis(1-pentyl-1H-benzimidazol-2-yl-κN3)phenyl-κC1]tellurium(II) (1,4-dioxane)triiodidomercurate(II)

In the title salt, (C34H41N4Te)[HgI3(C4H8O2)], the aryltellurenium [C34H41N4Te]+cations and [HgI3(dioxane)]−anions are linked by a short interaction between the Te atom and one of the I-atom donors of the anion, as well as through weak C—H...I interactions. The geometry around the Te atom is T-shaped with the coordination comprising a C atom of the central aromatic ring and two N atom donors of the benzimidazolyl moiety. The Te—N bond lengths are almost equal [2.232 (3) and 2.244 (3) Å], while the Te—C bond length is 2.071 (4) Å. The N—Te—N bond angle is 150.68 (11)°. The HgIIatom of the anion is coordinated by iodide ions from three sides and the fourth coordination site is occupied by an O atom of the solvent molecule (dioxane). Thus, it attains a trigonal–pyrimidal geometry, with O—Hg—I angles ranging of 90.76 (8) and 96.76 (7)° and I—Hg—I angles ranging from 112.41 (1) to 125.10 (1)°. The cations and anions are involved in numerous weak π–π stacking interactions involving both the central phenyl ring and two inversion-related benzimidazole moieties, which propagate in thea-axis direction. In addition, there are numerous C—H...I interactions between the cations and anions, which link them into a complex three-dimensional array.

Structure of the mercury(II) mixed-halide (Br/Cl) complex of 2,2′-(5-tert-butyl-1,3-phenylene)bis(1-pentyl-1H-benzo[d]imidazole)

The mercury(II) complex of 2,2′-(5-tert-butyl-1,3-phenylene)bis(1-pentyl-1H-benzimidazole), namelycatena-poly[[dihalogenidomercury(II)]-μ-2,2′-(5-tert-butyl-1,3-phenylene)bis(1-pentyl-1H-benzimidazole)-κ2N3:N3′], [HgBr1.52Cl0.48(C34H42N4)],2, has a polymeric structure bridgingviathe N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the orthorhombic space groupPca21and is a racemic twin [BASF = 0.402 (9)]. The geometry around the HgIIatom is distorted tetrahedral, with the HgIIatom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl). For the two ligands in the asymmetric unit, there is disorder with one of the twotert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2):0.43 (2) for thetert-butyl group and 0.73 (3):0.27 (3) for the benzimidazole group. In addition, there is threefold disorder for two of the fourn-pentyl groups, with occupancy factors of 0.669 (4):0.177 (4):0.154 (4) and 0.662 (4):0.224 (4):0.154 (4), respectively. The molecules form a one-dimensional helical polymer propagating in theb-axis direction. The helices are held together by intra-strand C—H...Br and C—H...Cl interactions. Each strand is further linked by inter-strand C—H...Br and C—H...Cl interactions. In addition, there are weak C—H...N inter-strand interactions which further stabilize the structural arrangement.

Packing forces in dichloridobis(3,5-diphenyl-1H-pyrazole-κN2)cobalt(II) dichloromethane hemisolvate

The title compound, [CoCl2(C15H12N2)2]·0.5CH2Cl2, was crystallized from a binary mixture of dichloromethane and hexane and a dimeric supramolecular structure was isolated. The CoIIcentre exhibits a distorted tetrahedral geometry, with two independent pyrazole-based ligands occupying two coordination sites and two chloride ligands occupying the third and fourth coordination sites. The supramolecular structure is supported by complementary hydrogen bonding between the pyrazole NH group and the chloride ligand of an adjacent molecule. This hydrogen-bonding motif yields a ten-membered hydrogen-bonded ring. Density functional theory (DFT) simulations at the PBE/6-311G level of theory were used to probe the solid-state structure. These simulations suggest that the chelate undergoes a degree of conformational distortion from the lowest-energy geometry to allow for optimal hydrogen bonding in the solid state.

Palladium(II) Complex of the 5-Hydroxypyridine-2-carbaldehyde N(4)-ethylthiosemicarbazone: Synthesis and Characterization

The novel complex of 5-hydroxypyridine-2-carbaldehyde N(4)-ethylthiosemicarbazone (HPyEt) with plalladium(II) have been prepared and characterized by elemental analysis, IR, 1H-NMR, UV-visible spectroscopy and mass spectrometry (FAB). Coordination of the anionic thiosemicarbazone ligand is via the pyridyl nitrogen, imine nitrogen and thiolato sulfur atoms and the fourth coordination site being occupied by chloride ion in square planar geometry. DOI: http://dx.doi.org/10.3126/jncs.v28i0.8040 Journal of Nepal Chemical Society Vol.28, 2011 Page 34-41 Uploaded date: March 6, 2013

Dimethyl Sulfoxide Containing Platinum(II) and Palladium(II) Chelate Complexes of Glyoxylic and Pyruvic Acid Thiosemicarbazones. A New Class of Cytotoxic Metal Complexes

The complexes [Pt(DMSO)(GT)]·DMSO (1), [Pt(DMSO)(PT)]· 1/2 DMSO (2) and [Pd(DMSO)- (PT)] (3), where DMSO = dimethyl sulfoxide, H2GT = glyoxylic acid thiosemicarbazone and H2PT = pyruvic acid thiosemicarbazone, have been synthesized and characterized by elemental analysis, molar electric conductivity, IR, electronic and NMR (1H and 13C) spectra. The single crystal X-ray diffraction analysis has revealed for 1 (orthorhombic, Pnma, a = 12.941(3), b = 7.108(2), c = 15.148(3) Å , Z = 4) that the doubly deprotonated thiosemicarbazone molecule is coordinated to Pt(II) via the carboxylato O, azomethine N and thiolato S atoms forming two condensed fivemembered chelate rings. The fourth coordination site of Pt(II) is occupied by the S atom of DMSO. All the atoms of the complex molecule are coplanar except the methyl groups. The O atom of DMSO is in cis-position towards the thiolato-S atom (point group Cs). A system of hydrogen bonds of the type N-H· · ·O links the complex molecules between them and with the lattice DMSO molecules. Similar structures have been deduced for the remaining two complexes on the basis of spectroscopic data. The three complexes and the ligand H2GT exhibit cytotoxic activity against F4N leukemia cells, whereas the ligand H2PT is inactive.