Alkali-metal hydrogen selenate-phosphates M 2 H 3(SeO4)(PO4) (M = Rb or K) and M 4H5(SeO4)3(PO4)(M = K or Na)

Crystalline hydrogen selenate-phosphates M ₂H₃(SeO₄)(PO₄) [M = Rb (I) or K (II)] and M ₄H₅(SeO₄)₃(PO₄) [M = K (III) or Na (IV)] were obtained by reactions of Rb, K, and Na carbonates with mixtures of selenic and phosphoric acid solutions. The X-ray structure study of single crystals revealed that I and II are isostructural (sp. gr. Pn). In these structures, SeO₄ and H₃PO₄ tetrahedra are linked by hydrogen bonds to form corrugated layers. Structures III and IV (sp. gr. $P\bar 1$ ) have similar arrangements of non-hydrogen atoms but different hydrogen-bond systems. In III = K₄(HSeO₄)₂{H[H(Se,P)O₄]₂}, the HSeO₄ groups branch from the infinite anionic {H[H(Se,P)O₄]₂} chains. In IV = Na₄[H(SeO₄)₂]{H[H_1.5(Se, P)O₄]₂}, the anionic {H[H_1.5(Se,P)O₄]₂} chains are crosslinked by hydrogen bonds formed by the [H(SeO₄)₂] dimers.     

Mutation L232H Promotes Chromophore Maturation of EGFP-Based Fluorescent Fusion Proteins

The L232H mutant of the enhanced green fluorescent protein (EGFP) was expressed and crystallized. An X-ray diffraction data set was collected from the crystals to 1.53 Å resolution. An analysis of the three-dimensional structure revealed a stacking interaction between the amino-acid residues Н78 and Н232, which contributes to the fastening of the C-terminal region of the protein in the vicinity of the chromophore and influences chromophore maturation of hybrid fluorescent proteins produced by fusion of the target proteins with the C-terminus of EGFP. This hypothesis was experimentally confirmed by investigating chromophore maturation of the hybrid proteins fused to the N- and C-termini of EGFP and EGFP-L232H.     

X-ray and neutron diffraction studies of the hydridotriruthenium cluster complex (μ-H)Ru3(CO)7(μ-As(C6H5)CH2As(C6H5)2) ((C6H5 2AsCH2As(C6H5)·CH2Cl2: an example of dibridged metal-metal bond M(μ-H)(μ-X)M,involving a heavy bridgehead atom

The title compound is (μ-H)Ru₃(CO)₇(μ-As(C₆H₅)CH₂As(C₆H₅)₂)((C₆H₅)₂ AsCH₂As(C₆H₅)₂)·CH₂C1₂. Crystal data: monoclinic,P2₁/n, cell parameters (X-ray)a=12.82(2) Å,b=22.91(2) Å,c=17.83(2) Å, β=99.1(3)°; (neutron)a=12.94(1) Å, β=22.95(2)Å,c=17.93(3)Å,β=99.55(5)°. The structure was solved from X-ray data. FinalR indices areR(F)=0.051,R _w (F)=0.049 (X-ray);R(F)=0.064,R _w (F)=0.048,R(F ²)=0.072,R _w (F²)=0.088 (neutron). The complex is derived from Ru₃(CO)₈(dpam)₂ through reaction with hydrogen. The structure consists of a triangular array of metal atoms involving three metal-metal bonds[Ru(1)?Ru(2)=2.912(7)Å;Ru(1)?Ru(3)=2.829(3) A; Ru(2)?Ru(3)=2.845(6) Å]. The metal-metal edge Ru(1)?Ru(2) is supported by a bridging bis(diphenylarsino)methane ligand which lies in the equatorial plane. Activation of the second dpam ligand has generated the new face-bridging ligand unit μ-As(C₆H₅)CH₂As(C₆H₅)₂. In this unit, the bridgehead As atom spans over the Ru(1)?Ru(2) bond, while the second As atom is only bonded to Ru(3). The metal environment is achieved by CO ligands. The hydride ligand is bridging the Ru(1)?Ru(2) vector [Ru(1)?H=1.791(10) Å; Ru(2)?H=1.818(8) Å]. Geometric features of the dibridged Ru(μ-H)(μ-As)Ru bond are discussed.     

Crystal structure of a mutant of archaeal ribosomal protein L1 from Methanococcus jannaschii

The crystal structure of a mutant of archaeal ribosomal protein L1 from Methanococcus jannaschii with the deletion of a nonconserved positively charged cluster consisting of eight C-terminal amino acid residues is determined by the molecular replacement method at 1.75 Å resolution. This mutant is shown to form more stable and ordered crystals belonging to a space group other than that of the wild-type protein crystals. The positively charged C-terminal region has only a slight effect on the interaction between protein L1 and RNA molecules. Hence, this mutant can be used to prepare protein-RNA complexes and obtain their crystals.     

Synthesis and crystal structures of bimetallic hydrogen sulfates M I M II [H(SO4)2](H2O)2 (M I = K, Cs; M II = Zn, Mn) and selenate KMg[H(SeO4)2](H2O)2

Single crystals of acid salt hydrates M ^I{M ^II[H(XO₄)₂](H₂O)₂}, where M ^I, M ^II, and X are K, Zn, and S (I); K, Mn, and S (II); Cs, Mn, and S (III); or K, Mn, and Se (IV), respectively, were synthesized and studied by X-ray diffraction analysis. Compounds I–IV (space group $P\bar 1$ ) are isostructural to each other and to hydrate KMg[H(SO₄)₂](H₂O)₂ (V) studied earlier. Structures I–V, especially, the M ^I-O, M ^II-O, and X-O distances and the O?H?O (2.44–2.48 Å) and O_w-H?O (2.70–2.81 Å) hydrogen bonds, are discussed.     

Modeling of the structure of ribosomal protein L1 from the archaeon <Emphasis Type="Italic">Haloarcula marismortui</Emphasis>

The halophilic archaeon Haloarcula marismortui proliferates in the Dead Sea at extremely high salt concentrations (higher than 3 M). This is the only archaeon, for which the crystal structure of the ribosomal 50S subunit was determined. However, the structure of the functionally important side protuberance containing the abnormally negatively charged protein L1 (HmaL1) was not visualized. Attempts to crystallize HmaL1 in the isolated state or as its complex with RNA using normal salt concentrations (≤500 mM) failed. A theoretical model of HmaL1 was built based on the structural data for homologs of the protein L1 from other organisms, and this model was refined by molecular dynamics methods. Analysis of this model showed that the protein HmaL1 can undergo aggregation due to the presence of a cluster of positive charges unique for proteins L1. This cluster is located at the RNA–protein interface, which interferes with the crystallization of HmaL1 and the binding of the latter to RNA.     

X-ray crystal and molecular structure of dichlorobis [2(1H)-pyridinethione-S]iron(II)

Attempts to prepare the mixed ligand complex, FeCl₂(pyS)(Ph₃P)₂ from the reaction of iron(III) chloride with 2(1H)-pyridinethione-S(HpyS) and triphenylphosphine(Ph₃P) in ethanol instead formed FeCl₂(HPyS)₂ characterized by X-ray crystallography. The structure was determined by the heavy atom method, using MoK diffractometer data, and refined by full-matrix least squares toR=0.049 for 1123 observed reflections. The molecule possesses twofold symmetry with a distorted tetrahedral geometry about the iron(II) center with S-Fe-S and Cl-Fe-Cl bond angles of 98.76(5)° and 115.79(5)° and Fe-S and Fe-Cl bond distances 2.345(1) Å and 2.288(1) Å, respectively. Hydrogen bonding between NH and chlorine atoms leads to a polymeric type structure of linked molecules running approximately parallel to thea axis.     

Crystal structure of M(II) bis-μ-diacetoamidopropionate,diaqua·4H2O (M=Cu,Zn, Co): An uncommon carbonyl-O-of-peptide-coordinated two-dimensional layered polymer

Crystal and molecular structures by X-ray diffraction analysis of Co, Cu and Zn complexes of 2,2-diacetoamidopropionic acid are reported. The results show that an uncommon bond from metal ion to a carbonyl-O-of-peptide atom is formed. The structures are isomorphic (Monoclinic,P2₁/c, with two formula units in the cell). The metal ion lies on a center of symmetry and it is six-oxygen coordinated in an octahedral-type configuration by pairs of water molecules, carboxylic (monodentate) groups and two carbonyl-O-of-peptide atoms. Ligand molecules bridge metal ions, so that the structure consists of a two-dimensional (sheet-type) polymer. Sheets are held together by a hydrogen-bond network making efficient use of the solvent water molecules.     

Crystallographic investigations of 1,4-benzothiazin-2(1H)one and 3-methyl-1,4-benzothiazin-2(1H)one

The crystal structures of 1,4-benzothiazin-2(1H)one (C₈H₇SNO) (I) and 3-methyl-1,4-benzothiazin-2(1H)one (C₉H₉SNO) (II) have been determined by X-ray diffraction methods. I crystallizes in the monoclinic system with space group P2₁/n, while II crystallizes in triclinic with space group P $\bar 1$ . The molecular features in both the structures are almost similar; however, there exists an intermolecular interaction in (II) that could be due to the methyl group.     

New zeotype borophosphates with chiral tetrahedral topology: (H)0.5M1.25(H2O)1.5[BP2O8]·H2O (M = Co(II) and Mn(II))

Two new isostructural open‐framework zeotype transition metal borophosphate compounds, (H)_0.5M_1.25(H₂O)_1.5[BP₂O₈]·H₂O (M = Co(II) and Mn(II)) were synthesized by mild hydrothermal method. The structure of compounds were characterized by single‐crystal X‐ray diffraction which have ordered, alternating, vertex‐sharing BO₄, PO₄, and (MO₄)OM(H₂O)₂ groups with hexagonal, P 6₁ 2 2 (No 178) space group and unit cell parameters for Co a = 9.4960(6) Å, c = 15.6230(13) Å, for Mn a = 9.6547(12) Å, c = 15.791(3) Å, Z = 1 for both of them. TGA/DTA analysis, IR spectroscopy were used for characterization. Magnetic susceptibility measurements for both of the compound indicate strong antiferromagnetic interaction between metal centers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Bimetallic hydrogen sulfates K4 M II[H(SO4)2]2(H2O)2 (M II = Mn or Zn)

Hydrogen sulfate hydrates K₄{M ^II[H(SO₄)₂]₂(H₂O)₂}, where M ^II = Mn or Zn, are synthesized, and their single-crystal structures are determined by X-ray diffraction. The structural units of the orthorhombic crystals (space group Pccn) are potassium and M ^II cations, SO ₄ ^2? and HSO ₄ ^? anions, and water molecules. Strong (2.52 Å) and moderate-in-strength (2.71–2.75 Å) hydrogen bonds link the anions and water molecules into hexamers. The M ^II cations, which have the octahedral environment (Mn-O, 2.14–2.19 Å and Zn-O, 2.07–2.11 Å), link the hexamers into flat layers. The structures of bimetallic hydrogen chalcogenate hydrates with different compositions are compared.     

Crystal Structure of 4-Amino-3-(thiophen-2-ylmethyl)-1H-1,2,4-triazole-5(4H)one Monohydrate

The molecular structure of the 4-amino-3-(thiophen-2-ylmethyl)-1H-1,2,4-triazole-5(4H)one monohydrate was determined by X-ray diffraction. The compound crystallizes in the monoclinic sp. gr. C2/c with Z = 4 in the unit cell. The title compound is not planar. The dihedral angle between the thiophene and 1,2,4-triazole rings is 73.4(5)°. In the crystal structure, the molecules are connected by intermolecular N–H···O, N–H···N, O–H···O, and C–H···N type hydrogen bonds. The N–H···N and C–H···N hydrogen bonds link the molecules into infinite chains along the c axis.     

Biscyclopentadienides with transition metal-mercury bonds. II: Dithiocarbamato derivatives of molybdenum and tungsten,and X-ray structure of (η5-C5H5)2Mo[HgS2CN(C2H5)2]2

The reactions in THF or benzene between Cp₂ M (HgX)₂ ·x HgX ₂ (M = Mo or W; O ?x ? 1;X ^? = Cl^?, Br^?, I^?, SCN^?, OAc^?) and sodium diethyl-dithiocarbamate $$\begin{gathered} Cp_2 M\left( {HgX} \right)_2 .xHgX_2 + \left( {2 + x} \right)Nadtc \rightleftharpoons Cp_2 M\left( {Hgdtc} \right)_2 \hfill \\ + xHg\left( {dtc} \right)_2 + \left( {2 + x} \right)NaX \hfill \\ \end{gathered} $$ as well as between Cp₂ MH₂ and mercury diethyldithiocarbamate $$x2Cp_2 MH_2 + 2Hg\left( {dtc} \right)_{2 - } Cp_2 M\left( {Hgdtc} \right)_2 + \left\{ {Cp_2 Mdtc} \right\}dtc + 2H_2 $$ give the compound Cp₂ M(Hgdtc)₂ (dtc is diethyldithiocarbamate anion). The structure of the molybdenum complex determined by the X-ray method (a = 12.776(4),b = 7.835(4),c = 27.397(7) Å β = 111.18(2) °; space groupC2/c (No. 15);Z = 4) consists of discrete molecules occupying special positions on two-fold axes. A short Mo-Hg distance of 2.643(8) Å and a rather long Hg-S one of 2.50(2) Å were found. The diethyldithiocarbamate anion behaves like a monodentate ligand. IR and¹H,¹³C NMR results agree with the molecular structure determination and confirm a weak bond between mercury and dithiocarbamate and strong molybdenum-mercury bond. A considerable solvent effect (C₆D₆ vs. CDCl₃ solutions) has been observed on the¹H chemical shifts of both dtc and Cp ligands. The {Cp₂Modtc}⁺ X ^? (X = dtc and PF₆) complexes, although not obtained in a pure form, were included in the discussion of the spectroscopic features of those with theM-Hg bonds.     

Structure of the [Co(NioxH)2(PPh 3)2]F complex

Compound [Co(NioxH)₂(PPh ₃)₂]F is synthesized in the CoF₂ · 4H₂O-NioxH₂-PPh ₃ system (where NioxH is the 1,2-cyclohexanedione dioxime monoanion and PPh ₃ is triphenylphosphine), and its structure is determined by X-ray diffraction. It is shown that the cobalt atom has the octahedral environment. Two nioxime residues that are related by the center of symmetry lie in the equatorial plane and are linked by the O-H?O hydrogen bond. The 1,6-positions of the octahedron are occupied by the phosphorus atoms of the triphenylphosphine ligands. The formation of the crystal structure of this compound is discussed.     

Crystal and molecular structure of a cobalt(II) complex with bis(benzimidazol-2-ylmethyl)-methylamine (L)

The reaction product of Co(II) chloride and the title ligand L, formulated as CoLCl₂·CH₃OH, was prepared and characterized by means of structural and spectroscopic measurements. The violet crystals are orthorhombic, (space groupP2₁2₁2₁) witha=8.093(2),b=14.883(3),c=16.831(3) Å, andZ=4. The structure consists of discrete molecules with pseudo-, noncrystallographic twofold symmetry in which the Co atom is coordinated in trigonal bipyramidal geometry by three nitrogen and two chlorine atoms. The ligand L is coordinated to the Co atom in afac mode and two chlorine atoms are incis-positions. The structure was confirmed by IR-spectra.     

Crystal structures of the methanol and hexanol adducts of tris(8-quinolinolato)manganese(III)

Both the methanol and hexanol adducts of tris(8-quinolinolato)manganese (III) have been shown to be isomorphic. They crystallize in the monoclinic space groupP2₁/n with four molecules in the unit-cell. The cell dimensions of the methanol adduct area= 10.847(3),b= 13.201(4),c= 17.285(5) Å β = 97.56(5) °; the asymmetric molecular unit being Mn(C₉H₆NO)₃.CH₃OH. For the hexanol adduct,a =11.201(4),b=13.342(4),c = 17.200(5) Å, β = 97.09(6) °, with an asymmetric molecular unit, Mn(C₉H₆NO)₃ · 1/2(C₆H₁₃OH). The methanol adduct structure was deduced from CuKα. intensities visually estimated from Weissenberg films, but refined on data rerneasured on a four-circle diffractometer. Data measured with Mokα radiation on a diffractometer was used for the analysis of the hexanol adduct. Both structures were solved by the heavy-atom method and refined by difference and least-squares procedures. AnR of 0.079 for the 1536 observed terms of the methanol structure and anR of 0.063 for the 2509 observed terms of the hexanol structure were attained. The complexes are in themeridional conformation, with the manganese atoms coordinated to the bidentate 8-quinolinol ligands in a distorted octahedral configuration. In the methanol structure, two methanol molecules related by the crystallographic center of symmetry lie in a “cage-like” cavity in the crystal structure, whereas in the hexanol structure only one hexanol molecule is so accommodated. The latter is disordered, the crystallographically imposed symmetry requiring that it adopts two orientations in the unit-cell.     

Comment on ‘Post UV irradiation annealing of E′ centers in silica controlled by H2 diffusion’ by M. Cannas et al. [J. Non-Cryst. Solids 337 (2004) 9–14]

In the paper by Cannas et al. [M. Cannas, S. Costa, R. Boscaino, F.M. Gelardi, J. Non-Cryst. Solids 337 (2004) 9] the simplest version of the Waite theory of diffusion limited reactions was applied to the post irradiation annealing of E′ centers by molecular hydrogen diffusing in a silica matrix. This version of the Waite theory does not take into account limitations arising from the rate of the chemical process between reactants but assumes that the annealing kinetics is limited by the diffusion only. An attempt to fit the annealing rate determined experimentally to that calculated from this version of the Waite theory led to an unrealistically small value of the capture radius. To clarify this issue, a more advanced version of the Waite theory, which takes into account the viability of the chemical reaction between H2 and E′ centers, should be used. In this comment such a version of the Waite theory is outlined and applied to an interpretation of the experimental data reported in [M. Cannas, S. Costa, R. Boscaino, F.M. Gelardi, J. Non-Cryst. Solids 337 (2004) 9]. A rigorous argument of the hypothesis introduced in paper [M. Cannas, S. Costa, R. Boscaino, F.M. Gelardi, J. Non-Cryst. Solids 337 (2004) 9] that the annealing kinetics of E′ centers is not limited by the diffusion of H₂ molecules but is defined by the rate of the chemical reaction itself is presented.     

Solid-phase synthesis and crystal structure of 5(3-nitrophenyl)-3,7-diphenyl-4H,6H-1,2-diazepine

The title compound, 5-(3-nitrophenyl)-3,7-diphenyl-4H,6H-1,2-diazepine (C₂₃H₁₉N₃O₂), was synthesized, in 76% yield, by one-pot multicomponent solid-phase reaction of 3-nitrobenzylidene phenyl ketone, acetophenone and hydrazine, using the catalyst bismuth nitrate, co-catalyst ZnCl₂, adsorbed on neutral alumina, at 110°C. The compound was characterized by spectral methods and X-ray diffraction studies. The crystals are monoclinic, space group P2₁/c: a = 12.186(2), b = 14.769(3), c = 11.046(2) Å, β = 115.023(3)°, Z = 4; R = 0.0418 for 2576 observed reflections. The diazepine ring assumes a twist chair conformation. The dihedral angles between the mean planes through the diazepine ring and the nitrophenyl rings and two phenyl are: 89.19(5)°, 45.85(5)° and 20.80(6)°, respectively. The crystal structure is stabilized by C-H…N, C-H…O, C-H…π hydrogen bonds and π-π-stacking interactions.     

X-ray diffraction, spectroscopic and DFT studies of 1-(4-bromophenyl)-3,5-diphenylformazan

The crystal structure of 1-(4-bromophenyl)-3,5-diphenylformazan was determined by X-ray single crystal diffraction technique. The crystals are orthorhombic, a = 23.0788(9), b = 7.9606(3), c = 18.6340(12) Å, Z = 8, sp. gr. Pbca, R ₁ = 0.074. The structure was also examined using the density-functional theory. Its structure stability, and frontier molecular orbital components were discussed and the results were compared with X-ray and spectral results. The maximum absorbtion peaks of the UV-vis spectrum of the compound have been calculated using the time-dependent density-functional theory. It was found a good agreement between the calculated and experimental maximum absorption wavelength.     

Crystal structure of 4,5-dihydro-6-(2-thienyl)-3(2H) pyridazinone azine, (C16H16N16S2)

M_r = 484, monoclinic, P 2₁/c, a = 5.567(1), b = 7.857(2), c = 19.194(10) Å, β = 99.97(3)°, V = 826.9 ų, Z′ = 2, D_x = 1.43 g · cm⁻³, F(000) = 372, MoKα, λ = 0.71069 Å, μ = 0.328 mm⁻¹, final R = 0.055 for 889 observed reflections, T = 293 K. The compound was prepared from a direct unusual reaction of 6-(2-thienyl)-2,3,4,5-tetrahydropyridazine-3-one with hydrazine hydrate. The structure was solved by direct methods and refined by full-matrix least squares. The molecule in the solid state consists of a dimer with its two equivalent halves related by a center of symmetry at the middle of the N N bond. Each molecular fragment is nearly planar and the N N bond between the two halves is 1.296(5) Å indicating that it is a partial double bond.