The structure of chromium potassium alum

1958 ◽  
Vol 246 (1244) ◽  
pp. 78-90 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Water Molecule ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
Potassium Alum ◽  
X Ray ◽  
Single Crystal Study ◽  
Thermal Vibrations ◽  
Oxygen Atoms

A single-crystal study of chromium potassium alum has been made by neutron diffraction, thus completing the structure first indicated by the X-ray investigations of Lipson & Beevers (1935). Hydrogen bonds link the oxygen atoms within the water molecules to other oxygen atoms in the structure. In each case the angle HOH for a water molecule is about 106°, although this sometimes entails appreciable displacement of the hydrogen atoms from the direct O—O line. Large thermal vibrations of the oxygen atoms in the sulphate groups are noteworthy.

NEUTRON DIFFRACTION DETERMINATION OF THE HYDROGEN POSITIONS IN NATROLITE

1964 ◽  
Vol 42 (2) ◽  
pp. 229-240 ◽  
Author(s):  
B. H. Torrie ◽  
I. D. Brown ◽  
H. E. Petch
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Oxygen Atom ◽  
Water Molecule ◽  
Neutron Diffraction Data ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Diffraction Determination

Neutron diffraction data obtained with single crystals of natrolite, Na2Al2Si3O10.2H20, have been analyzed using Fourier difference synthesis arid least squares methods. The details of the aluminosilicate framework were found to be in agreement with the results of earlier X-ray diffraction studies. The oxygen atom of the water molecule is linked by bent hydrogen bonds to two oxygen atoms in the framework, making an O—O—O angle of 134°. Lying almost in the O—O—O plane, the hydrogen atoms are located at distances of 0.94 ± 0.03 and 0.98 ± 0.02 Å from the oxygen of the water molecule and make with it an H—O—H angle of 108°. Natrolite thus provides an excellent example of the ability of the water molecule to resist the influence of the environment in opening the H—O—H angle.

Structure of Bis(isobutylammonium) Selenite and its Sesquihydrate

2006 ◽  
Vol 61 (11) ◽  
pp. 1401-1405
Author(s):  
Maren Wiechoczek ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bonds ◽  
Layer Structure ◽  
Selenium Dioxide ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Layer Structures ◽  
Graph Set ◽  
Ray Methods ◽  
Oxygen Atoms

Isobutylammonium selenite and its sesquihydrate were obtained in low yields by reaction of selenium dioxide with the neat amine in the presence of small amounts of water. Both structures were determined by X-ray methods and proved to contain two independent formula units. In both cases, layer structures [(CH3)2CHCH2NH3]2[SeO3] are formed in which all NH hydrogen atoms act as single hydrogen bond donors, and all selenite oxygen atoms accept two hydrogen bonds. The layers contain six independent rings; the anhydrous substance has all rings of graph set R34 (10), whereas the sesquihydrate has two each of R44 (12), R24 (8) and R34 (10). The three independent water molecules of the sesquihydrate attach themselves to the layer structure by further classical hydrogen bonds to the selenite oxygen atoms.

Komplexe mit substituierten 2,5-Dihydroxy-p-benzochinonen: EA[C6(NO2)2O4] · H2O (EA = Ca, Sr)/ Complexes with Substituted 2,5-D ihydroxy-p-benzoquinones: EA [C6(NO2)2O4] · 4H2O(EA = Ca, Sr)

1987 ◽  
Vol 42 (8) ◽  
pp. 972-976 ◽  
Author(s):  
Christian Robl
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Single Crystals ◽  
Coordination Sphere ◽  
Trigonal Prism ◽  
Water Molecules ◽  
Additional Water ◽  
Oxygen Atoms

AbstractSingle crystals of EA[Q(NO2)2O4] · 4H2O (EA = Ca. Sr) were grown in aqueous silicagel. Ca2+ has CN 8. It is surrounded by 4 oxygen atoms of two bis-chelating [C6(NO2)2O4]2- ions and 4 water molecules, which form a distorted, bi-capped trigonal prism. Sr2+ is coordinated similarly, with an additional water molecule joining the coordination sphere to yield CN 8+1. Corrugated chains extending along [010] and consisting of EA2+ and nitranilate ions are the main feature of the crystal structure. Adjacent chains are interlinked by hydrogen bonds.

Carbacylamidophosphates: Synthethis and Structure of N,N'-Tetramethyl-NM-benzoylphosphoryltriamide and Dimorpholido-N-benzoylphosphorylamide

2000 ◽  
Vol 55 (6) ◽  
pp. 495-498 ◽  
Author(s):  
Katerina E. Gubina ◽  
Vladimir A. Ovchynnikov ◽  
Vladimir M. Amirkhanov ◽  
Viktor V. Skopenkoa ◽  
Oleg V. Shishkinb
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
Sodium Salts ◽  
Space Group ◽  
X Ray ◽  
Centrosymmetric Dimers ◽  
Oxygen Atoms

N,N′-Tetramethyl-N"-benzoylphosphoryltriamide (I) and dimorpholido-N-benzoylphosphorylamide (II), and their sodium salts Nal, Nall were synthesized and characterized by means of IR and 1H, 31P NMR spectroscopy. The structures of I, II were determined by X-ray diffraction: I monoclinic, space group P2i/c with a = 10.162(3), b= 11.469(4), c = 12.286(4) Å , β = 94.04°, V = 1428.4(8) A 3, Z = 4, p(calcd) = 1.187 g/cm3; II monoclinic, space group C2/c with a = 15.503(4), b = 10.991(3), c = 22.000(6) Å, β = 106.39°, V = 3596.3(17) Å3, Z = 8, p(calcd.) = 1.253 g/cm3. The refinement of the structures converged at R = 0.0425 for I, and R = 0.068 for II. In both structures the molecules are connected into centrosymmetric dimers via hydrogen bonds formed by the phosphorylic oxygen atoms and hydrogen atoms of amide groups.

The crystal and molecular structure of guanine hydrochloride dehydrate

1965 ◽  
Vol 288 (1414) ◽  
pp. 418-439 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Chlorine Ions ◽  
Atomic Coordinates ◽  
Single Crystal Analysis

The structure of guanine hydrochloride monohydrate has been determined by X-ray single crystal analysis and the parameters (including anisotropic temperature vibrations) have been refined by the three-dimensional least squares method. The unit cell is monoclinic with a = 14.69 ± 0.01, b = 13.40 ± 0.01, c = 4.840 ± 0.005 Å; β = 93.8°± 0.1°; space group P 2 1 / a . For 1600 independent reflexions the final value of the agreement index R was 0.07 and the standard deviations of atomic coordinates are in the region of 0.0035 Å. Two guanine molecules are linked together by hydrogen bonds to form a centrosymmetrical dimer. The dimer is linked by hydrogen bonds to four water molecules which are then hydrogen bonded to two chlorine ions. It is shown that the guanine molecule has associated with it six centres of electron density corresponding to hydrogen atoms and it is therefore in the form (H guanine) + with protonation at the N 7 position.

A neutron diffraction study of mercury(II)chromate hemihydrate, HgCrO4 · 1/2 H2O

1975 ◽  
Vol 142 (3-4) ◽  
Author(s):  
Karin Aurivillius ◽  
Claes Stålhandske
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Water Molecule ◽  
Diffraction Study ◽  
Neutron Diffraction Study ◽  
Mercury Atom ◽  
Building Elements ◽  
Oxygen Atoms

AbstractThe crystal structure of mercury(II)chromate hemihydrate, HgCrOThe mercury atom is bonded only to two oxygen atoms, each belonging to a separate Chromate tetrahedron, at the distances 2.055(2) and 2.064(2) Å, the angle O–Hg–O being 179.95(5)°. As each Chromate group is bonded to two mercury atoms, fundamental building elements of the structure are endless chains of the composition (HgCrOIn the water molecule the distances O(W)–H (2 × ) and H–H are 0.945(4) and 1.487(6) Å respectively. The angle H–O(W)–H is 103.7(4)°. In the hydrogen bonds the distance O(W)–H…O between water and Chromate oxygen atoms is 2.961(2) Å with a distance H…O of 2.133(4) Å and an angle O(W)–H…O of 145.6(3)°.

Spin density and bonding in Mn(H 2 O) 2+ 6 in ammonium manganese Tutton salt

1986 ◽  
Vol 404 (1826) ◽  
pp. 127-138 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Manganese Atom ◽  
Water Molecules ◽  
Spin Component ◽  
Hydrogen Atoms ◽  
Spin Distribution ◽  
Overlap Population ◽  
Structure Factors ◽  
D Orbitals ◽  
Oxygen Atoms

The structure of (NH 4 ) 2 Mn(SO 4 ) 2 6H 2 O has been determined at 4.2 K by neutron diffraction. It confirms the main features of an earlier X-ray structure and gives details of the water molecules and the hydrogen bonding. The flipping ratios associated with the more intense Bragg reflections were measured by polarized neutron diffraction. By using the neutron structure factors, 495 unique magnetic structure factors were obtained and the spin distribution in the Mn(H 2 O) 2+ 6 ion was modelled. There appears to be no reduction in spin population in the Mn 2+ d-orbitals (t 3.1 2g e 2.0 g ), but a small negative diffuse population, 4s 0.2 -, is present, which together with a total ‘overlap’ population of –0.1 spins balances the 0.2 net positive spin found on the water molecules. Unexpectedly, the spin on the water molecules seems to be concentrated on the side of the oxygen atoms far from the manganese atom, and to reside more on the hydrogen atoms than the oxygen atoms. Evidence for the expected negative spin component in the Mn—O bonds arising from antibonding overlap is found.

About the degree of hydration in potassiumtrisoxalatochromate hydrate

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Chunhua Hu ◽  
Gernot Heger ◽  
Irmgard Kalf ◽  
Ullrich Englert
Keyword(s):  
Neutron Diffraction ◽  
Water Molecules ◽  
Structure Model ◽  
Hydrogen Atoms ◽  
Neutron Data ◽  
X Ray ◽  
Degree Of Hydration ◽  
Thermogravimetric Data ◽  
Hydration Model ◽  
Good Agreement

AbstractData obtained from single crystal X-ray and neutron diffraction experiments have been combined with results from thermogravimetry in order to derive an improved structure model for potassium tris(oxalato)chromate hydrate. The degree of hydration for this compound has been reinvestigated: Earlier work assumed a trihydrate stoichiometry and had to accept an unusually short K···O distance of 2.3 Å. Our neutron data reveal the position of the hydrogen atoms in the water molecules; they prove that abnormally short separations between a cation and atoms of a water molecule can only occur between sites of mutually exclusive occupancy and hence remain without chemical relevance. Closest K···O distances in our revised hydration model amount to 2.6 Å, in good agreement with expectation. Both diffraction experiments and thermogravimetric data agree with the stoichiometry K

Preparation and Crystal Structures of Two Dimeric Lanthanoid(III) Complexes Containing Pyridinioacetate and 2,2'-Bipyridine Ligands:[Ln2( bpy )2( pybet )4(H2O)4] ( bpy )3(ClO4)6.H2O (Ln = Eu and Tb)

1995 ◽  
Vol 48 (9) ◽  
pp. 1643 ◽  
Author(s):  
XM Chen ◽  
YL Wu ◽  
YS Yang
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecule ◽  
Crystal Structures ◽  
Lattice Water Molecule ◽  
X Ray ◽  
Bond Lengths ◽  
X Ray Crystallography ◽  
Lattice Water ◽  
Oxygen Atoms

Two dimeric lanthanoid (III) complexes, [Ln2( bpy )2( pybet )4(H2O)4] ( bpy )3(ClO4)6.H2O ( bpy = 2,2′-bipyridine, pybet = pyridinioacetate, and Ln Eu and Tb), have been prepared and characterized by X-ray crystallography. The complexes are isostructural, each comprising a quadruply carboxylato -bridged, centrosymmetrical dimeric cation, six perchlorate anions, three uncoordinated bpy molecules and a lattice water molecule. Each Ln ion is surrounded in a distorted square-antiprismatic environment by four carboxylato oxygen atoms, two nitrogen atoms of the bidentate bpy ligand and two aqua ligands . The Ln-O bond lengths range from 2.33 to 2.44 Ǻ, and Ln-N bond lengths from 2.55 to 2.64 Ǻ. The uncoordinated bpy molecules are linked to the aqua ligands by hydrogen bonds.

Opening and Narrowing of the Water H—O—H Angle by Hydrogen-Bonding Effects: Re-inspection of Neutron Diffraction Data

1998 ◽  
Vol 54 (4) ◽  
pp. 464-470 ◽  
Author(s):  
T. Steiner
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Diffraction Data ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Secondary Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sample Average

For 71 water molecules donating two Ow—H...O hydrogen bonds, the correlation of the covalent H—O—H angle and the O...Ow...O angle is inspected from 49 well refined organic and organometallic neutron diffraction crystal structures. Compared to sample average, the water angle is opened for large and narrowed for small O...Ow...O angles. Notably, the H—O—H angle is widened compared with the gas phase value even for small O...Ow...O. Related behavior is observed for chloride anion acceptors. The correlation exhibits a considerable scatter which should not be interpreted as experimental inaccuracies, but as secondary effects. Possible secondary effects are multi-center hydrogen bonding and effects of coordination to the water O atom. In a comparative test, low-temperature X-ray diffraction data were shown to be completely unsuitable for this type of analysis. The dependence of the C—O—H angle on the C—O...O angle in hydrogen bonds donated by hydroxyl groups in carbohydrates is also shown.

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