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  • 1
    ISSN: 1573-1111
    Keywords: Crystal structure ; clathrate ; 4-methylpyridine ; Cu(II) ; Mn(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structures of the two clathrates with the composition [M(4-MePy)4(NCS)2]·0.67(4-McPy)·0.33 H2O (M=Cu(II), Mn(II); 4-MePy=4-methylpyridine) have been determined. These compounds are trigonal, with the [M(4-MePy)4(NCS)2] host molecules being centrosymmetric. The parameters of the unit cells area = 27.365(7) and 27.738(6),c = 11.303(9) and 11.250(8) Å,V = 7325(2) and 7493(2) Å3, space group R $$\bar 3$$ , R = 0.053 and 0.109 for M = Cu(II) and Mn(II), respectively. ForZ = 9d calcd is equal to 1.271 and 1.225 g/cm3, andd measd is equal to 1.252(2) and 1.213(2) g/cm3 for the Cu and Mn clathrates, respectively. The coordination environment of the metal atoms in these compounds is an irregular octahedron, while in the Mn compound these distortions are rather small (Mn-NMePy 2.30, 2.34 Å, Mn-NNCS 2.18 Å, and Cu-NMePy 2.06 Å, Cu-NNCS 1.98 Å and Cu-NMePy 2.50 Å). The molecular packing in the structures is such that the channels of variable diameter are formed along the short cell dimension (the maximum diameter is ≅ 10 Å, the minimum being ≅ 6 Å) where the guest 4-MePy and H2O molecules are placed.
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  • 2
    ISSN: 1573-1111
    Keywords: Crystal structure ; clathrate ; Werner complex ; isothiocyanate ; 4-methylpyridine ; Mg(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two clathrate modifications of the title host with 4-methylpyridine (4-CH3C5H4N) as a guest have been determined at −50°C. [Mg(4-CH3C5H4N)4(NCS)2] · 2/3(4-CH3C5H4N) · 1/3H2O is trigonal, space group $$R\bar 3$$ , witha=27.630(7),c=11.219(3) ÅV=7417(4) Å3,Z=9,D calc=1.171 g cm−3,μ(CuK α)=18.506 cm−1, finalR=0.064. [Mg(4-CH3C5H4N)4(NCS)2] · (4-CH3C5H4N) is tetragonal, space group I4l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D calc=1.191 g cm−3, μ(CuK α)=18.200 cm−1, finalR=0.071. The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.
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  • 3
    ISSN: 1573-1111
    Keywords: Crystal structure ; Werner clathrate ; azide ; pyridine ; Ni(II) ; Co(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract [MPy4(N3)2]⋅2Py (M = Ni, Co) are clathrates where two of six pyridine species are included in the crystal structure of the host complex without chemical bonding. The clathrates are isostructural, orthorhombic, space group Pnna (52), Z = 4. For the Ni compound a = 14.958(5), b = 11.909(5), c = 17.517(7) Ú, V = 3120(2) Ú3, µ = 12.25 cm-1, final R = 0.057.The Cocompound is of very similar structure (a = 14.980(3), b =11.980(2), c = 17.350(5) Ú, V = 3114(1) Ú3, µ = 46.50 cm-1. The metal cation in the host molecule is surrounded by six donor nitrogens of two terminal azido-groups in trans-positions and four pyridine ligands. The complex molecule lies on a twofold axis parallel to a.
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  • 4
    ISSN: 1573-1111
    Keywords: Crystal structure ; lanthanides ; praseodymium ; dimer ; macrocycle ; (2.2.1) ; cryptand ; NMR ; paramagnetic ion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A dimeric lanthanide cryptate was obtained by the addition of an excess of cryptand (2.2.1) to a slightly hydrated solution of the monomeric praseodymium (2.2.1) perchlorate complex in acetonitrile. This new lanthanide compound is centrosymmetric and displays the space groupP21/n. The encryptated metal ions are nine-coordinated, they are bonded to all the heteroatoms of a (2.2.1) ligand and they are linked to each other by two μ-hydroxo bridges. The hydroxyl groups are relegating the cryptands to both end of the dimer and the praseodymium ions are less effectively accomodated in the macrocylic internal cavities than in the case of the monomeric Pr(2.2.1) complex. The formation of both the monomeric and the dimeric lanthanide complexes is readily observed by proton NMR.
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  • 5
    ISSN: 1573-1111
    Keywords: Crystal structure ; single crystal ; chiral macrocycles ; cyclic polyethers ; mannopyranosides ; complexation ; host-guest interaction ; molecular mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of α-d-mannosido-benzo-18-crown-6·KSCN (1) was solved by X-ray single crystal diffractometry. C28H36O10·KSCN is orthorhombic, space groupP212121 withZ=4,a=8.035(4),b=9.960(2),c=38.83(2) Å,M r =629.8,V=3103.6 Å3,D x =1.347 g cm−3, μ(CuKα)=2.53 mm−1, λ=1.54178 Å,F(000)=1324. FinalR=0.043 for 1139 unique observed reflections measured at room temperature. The potassium ion is surrounded by a nearly planar hexagon of oxygen atoms of the macrocyclic ring and lies on the plane formed by those atoms. Hexagonal pyramidal coordination is completed by the nitrogen atom of the thiocyanate anion. The SCN ion was found on the face of the macrocyclic ring opposite that for the chiral mannopyranoside moiety. The molecular structure of α-d-mannosido-18-crown-6 (2) and the structure of molecular complexes of2 and α-d-glucosido-benzo-18-crown-6 (3) were studied by molecular mechanics methods. The results suggest enthalpy driven selectivity of complexation of the phenylalanine methyl ester (4) by2 and both enthalpy and entropy effects in selective complexation of4 by3.
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  • 6
    ISSN: 1573-1111
    Keywords: Crystal structure ; X-ray crystallography ; gossypol ; host-guest complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of the 1 : 1 lattice inclusion complex of gossypol with isovaleric acid has been determined by X-ray structure analysis. The crystals of C30H30O8⁗C5H10O2 are monoclinic, space groupC2/c,a=28.835(7),b=9.063(2),c=26.880(4)Å, β=109.66(1)°,V=6615(2) Å3,Z=8,D x = 1.25 g cm−3, μ(CuKα) = 7.14 cm−1,T = 295 K. The structure was solved by direct methods and refined with isotropic thermal parameters to the finalR value of 0.132 for 1114 observed reflections. Hydrogen bonded gossypol molecules form columns along the [1 0 1] direction. These columns pack into layers parallel to the (101) plane. The layers of gossypol molecules are separated by the layers of isovaleric acid. The acid molecules are connectedvia a pair of O-H...O hydrogen bonds forming centrosymmetric dimers. There is no hydrogen bond interaction between the carboxylic acid dimers and gossypol molecules.
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  • 7
    ISSN: 1573-1111
    Keywords: Crystal structure ; disorder ; ethylenediamine ; inclusion complex ; layered structure ; tetracyanonickelate ; twinning crystals ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of [Zn(en)2- (NC)2Ni(CN)2 Zn(en)][Ni(CN)4]· 3 H2O consists of infinite positively charged wave-shaped layers of composition [Zn(en)2-(NC)2Ni(CN)2- Zn(en)] n 2n+ with the [Ni(CN)4]2− anions and water molecules included between them. Both Ni atoms exhibit square-planar coordination. The chelate bonded en (=ethylenediamine) and N-bonded cyano ligands around two independent zinc atoms form a deformed tetrahedron and a deformed octahedron, respectively. Yellow needles of the complex belong to the orthorhombic space groupPbcm witha = 6.977(1),b = 25.407(4),c = 14.876(2)Å,Z = 4,D m = 1.74(1) g cm−3 andD c = 1.739 g cm−3. The structure was refined toR = 6.31 %.
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  • 8
    ISSN: 1573-1111
    Keywords: Crystal structure ; diaminononane ; Hofmann-danon-type ; o-xylene ; tetracyanonickelate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Hofmann-danon-typeo-xylene clathrate Cd[NH2(CH2)9NH2]Ni(CN)4·0.5(CH3)2C6H4, crystallizes in the triclinic space groupPĪ witha = 15.118(3),b = 14.048(4),c = 7.325(1) Å, α = 91.50(2), β = 131.66(3), and γ = 107.50(2)°,V = 1051(1) Å3 andZ = 2. The structure, refined toR = 0.047 using 2851 reflections, reveals a three-dimensional host framework built of the layers of a two-dimensionalcatena-[cadmium tetra-μ-cyanonickelate(Il)] network and of the ambidentate 1,9-diaminononane (danon) bridging the Cd atoms in adjacent networks. The guesto-xylene molecule is accommodated in the cavity formed in the interlayer space similar to that in the Hofmann-daotn-type. The skeleton of the danon in the Cd-NC9N-Cd linkage takes a (gauche)2(trans)8 conformation twisted at the (gauche)2 part in contrast with the all-trans conformation of 1,8-diaminononane in the Hofmann-daotn-type clathrate. The twisted (gauche)2 part of the danon skeleton occupies the interlayer space to such an extent that void space available for the guest o-xylene molecule decreases to half that in the Hofmann-daotn-type clathrate Cd[NH2(CH2)8NH2]Ni(CN)4·G.
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  • 9
    ISSN: 1573-1111
    Keywords: Crystal structure ; dicyanoargentate ; Hofinann-type clathrate ; inorganic host ; metal complex ; host ; mineralomimetic chemistry ; organic guest ; tetracyanocadmate ; tetracyanonickelate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract One-, two- and three-dimensional CN-bridged metal complex structures made up of building blocks such as linear [Ag(CN)2]−, square planar [Ni(CN)4]2− or tetrahedral [Cd(CN)4]2−, and of the complementary ligands such as ammonia, water, unidentate amine, bidentate a,w- diaminoalkane, etc., are reviewed with an emphasis on their behaviour as hosts to afford clathrate inclusion compounds with guest molecules and as self-assemblies to form supramolecular structures with or without guests. The historical background is explained for Prussian blue and Hofmann's benzene clathrate based on their single crystal structure determinations. The strategies the author and coworkers have been applying to develop varieties of clathrate inclusion compounds from the Hofmann-type are demonstrated with the features observed for the developed structures determined by single crystal X-ray diffraction methods.
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  • 10
    ISSN: 1573-1111
    Keywords: Crystal structure ; EXAFS ; clathrate ; 4-pyridine ; 2-pyridine ; Cu(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Powder samples of the new compound [Cu(C5H5N)4·Br2](C5H5N) and of its desorption product have been studied by EXAFS. The crystal structure of [Cu(C5H5N)4Br2]·(C5H5N) has been determined from three-dimensional X-ray diffraction data and refined to theR value 0.038 for 379 observed reflections. (orthorhombic,Ccca,a=12.033(8),b=14.764(3),c=16.768 Å,V=1897(3) Å3,Z=4). The copper atom lies on a 222 symmetry site and is hexacoordinated with four nitrogen and two bromine atoms, forming an elongated octahedron with the bromine atoms in apical positions (Cu−Br distance: 3.201(2) Å, Cu−N1/N2 distances: 2.02(1)/2,07(1) Å). The host molecules (Cu(C5H5N)4Br2) form layers parallel to the (001) plane. Cavities in the space between these layers, bound by pyridine ligands protruding into this space, are occupied by the guest molecules (C5H5N). The guest desorption at room temperature is accompanied by a chemical and structural destruction of the host, leading to the known compound Cu(C5H5N)2Br2.
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