The Hydrate of Hexafluorophosphoric Acid

1972 ◽  
Vol 50 (21) ◽  
pp. 3515-3520 ◽  
Author(s):  
D. W. Davidson ◽  
S. K. Garg

HPF6 is said to form a hexahydrate of a unique clathrate structure in which [Formula: see text] ions occupy truncated-octahedral cages in a framework of hydrogen-bonded water molecules. N.m.r. studies show, however, that appreciable quantities of HF are incorporated in the lattice and that the composition is more properly [Formula: see text], a result supported by chemical analysis. H3O+ and HF appear to be distributed over the lattice sites previously assigned to water molecules so as to involve all H atoms in the hydrogen bonding. The 1H resonance line is narrowed by rapid proton diffusion down to 150 °K. The 19F line of encaged [Formula: see text] is narrowed by rotation above 75 °K and reaches the rigid-lattice shape only below 25 °K.

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1369 ◽  
Author(s):  
Wang ◽  
Ke ◽  
Feng ◽  
Ho ◽  
Chang ◽  
...  

Two coordination polymers (CPs) with chemical formulas, [Ho2(C4O4)2(C2O4)(H2O)8]·4H2O (1) and [Ho(C4O4)1.5(H2O)3] (2), (C4O42− = dianion of squaric acid, C2O42− = oxalate), have been synthesized and their structures were determined by single-crystal X-ray diffractometer (XRD). In compound 1, the coordination environment of Ho(III) ion is eight-coordinate bonded to eight oxygen atoms from two squarate, one oxalate ligands and four water molecules. The squarates and oxalates both act as bridging ligands with 1,2-bis-monodentate and bis-chelating coordination modes, respectively, connecting the Ho(III) ions to form a one-dimensional (1D) ladder-like framework. Adjacent ladders are interlinked via O–HO hydrogen bonding interaction to form a hydrogen-bonded two-dimensional (2D) layered framework and then arranged orderly in an AAA manner to construct its three-dimensional (3D) supramolecular architecture. In compound 2, the coordination geometry of Ho(III) is square-antiprismatic eight coordinate bonded to eight oxygen atoms from five squarate ligands and three water molecules. The squarates act as bridging ligands with two coordination modes, 1,2,3-trismonodentate and 1,2-bis-monodentate, connecting the Ho(III) ions to form a 2D bi-layered framework. Adjacent 2D frameworks are then parallel stacked in an AAA manner to construct its 3D supramolecular architecture. Hydrogen bonding interactions between the squarate ligands and coordinated water molecules in 1 and 2 both play important roles on the construction of their 3D supramolecular assembly. Compounds 1 and 2 both show remarkable ligand-enhanced photo-induced color-changing behavior, with their pink crystals immediately turning to yellow crystals under UV light illumination.


2010 ◽  
Vol 66 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Maxime A. Siegler ◽  
Jacob H. Prewitt ◽  
Steven P. Kelley ◽  
Sean Parkin ◽  
John P. Selegue ◽  
...  

Five structures of co-crystals grown from aqueous solutions equimolar in 15-crown-5 (or 15C5) and [M(H2O)6](NO3) n , M = Al3+, Cr3+ and Pd2+, are reported. The hydrogen-bonding patterns in all are similar: metal complexes including the fragment trans-H2O—M—OH2 alternate with 15C5 molecules, to which they are hydrogen bonded, to form stacks. A literature survey shows that this hydrogen-bonding pattern is very common. In each of the two polymorphs of the compound [Al(H2O)6](NO3)3·15C5·4H2O there are two independent cations; one forms hydrogen bonds directly to the 15C5 molecules adjacent in the stack, while the other cation is hydrogen-bonded to two water molecules that act as spacers in the stack. These stacks are then crosslinked by hydrogen bonds formed by the three nitrate counterions and the three lattice water molecules. The hydrogen-bonded stacks in [Cr(H2O)5(NO3)](NO3)2·1.5(15C5)·H2O are discrete rather than infinite; each unit contains two Cr3+ complex cations and three 15C5 molecules. These units are again crosslinked by the uncoordinated nitrate ions and a lattice water molecule. In [Pd(H2O)2(NO3)2]·15C5 the infinite stacks are electrically neutral and are not crosslinked. In [Pd(H2O)2(NO3)2]·2(15C5)·2H2O·2HNO3 a discrete, uncharged unit containing one Pd complex and two 15C5 molecules is `capped off' at either end by a lattice water molecule and an included nitric acid molecule. In all five structures the infinite stacks or discrete units form an array that is at least approximately hexagonal.


2000 ◽  
Vol 56 (1) ◽  
pp. 142-154 ◽  
Author(s):  
Feng Xue ◽  
Thomas C. W. Mak

New crystalline adducts of tetraalkylammonium terephthalate/trimesate with urea and water molecules result from hydrogen-bond directed assembly of complementary acceptors and donors, and the anionic host lattices are described using the graph-set notation to identify distinct hydrogen-bonding motifs and patterns. Tetra-n-butylammonium terephthalate–urea–water (1/6/2), C46H104N14O12 (1), triclinic, space group P1¯, a = 8.390 (2), b = 9.894 (2), c = 18.908 (3) Å, α = 105.06 (2), β = 94.91 (1), γ = 93.82 (2)°, Z = 1, is composed of hydrogen-bonded terephthalate–urea layers, which are intersected by urea layers to generate a three-dimensional network containing large channels for accommodation of the cations. Tetraethylammonium terephthalate–urea–water (1/1/5), C25H58N4O10 (2), triclinic, P1¯, a = 9.432 (1), b = 12.601 (1), c = 14.804 (1) Å, α = 79.98 (1), β = 79.20 (1), γ = 84.18 (1)°, Z = 2, has cations sandwiched between hydrogen-bonded anionic layers. Tetraethylammonium trimesate–urea–water (1/2/7.5), C35H86N7O15.5 (3), triclinic, P1¯, a = 13.250 (1), b = 14.034 (1), c = 15.260 (1) Å, α = 72.46 (1), β = 78.32 (1), γ = 66.95 (1)°, Z = 2, manifests a layer-type structure analogous to that of (2). Tetra-n-propylammonium hydrogen trimesate–urea–water (1/2/5), C35H78N6O13 (4), orthorhombic, Pna21, a = 16.467 (3), b = 33.109 (6), c = 8.344 (1) Å, Z = 4, features hydrogen trimesate helices in a three-dimensional host architecture containing nanoscale channels each filled by a double column of cations.


2002 ◽  
Vol 66 (6) ◽  
pp. 1063-1073 ◽  
Author(s):  
R. L. Frost ◽  
W. Martens ◽  
P. A. Williams ◽  
J. T. Kloprogge

Abstract The molecular structure of the three vivianite-structure, compositionally related phosphate minerals vivianite, baricite and bobierrite of formula M32+(PO4)2.8H2O where M is Fe or Mg, has been assessed using a combination of Raman and infrared (IR) spectroscopy. The Raman spectra of the hydroxyl-stretching region are complex with overlapping broad bands. Hydroxyl stretching vibrations are identified at 3460, 3281, 3104 and 3012 cm−1 for vivianite. The high wavenumber band is attributed to the presence of FeOH groups. This complexity is reflected in the water HOH-bending modes where a strong IR band centred around 1660 cm−1 is found. Such a band reflects the strong hydrogen bonding of the water molecules to the phosphate anions in adjacent layers. Spectra show three distinct OH-bending bands fromstrongly hydrogen-bonded, weakly hydrogen bonded water and non-hydrogen bonded water. The Raman phosphate PO-stretching region shows strong similarity between the three minerals. In the IR spectra, complexity exists with multiple antisymmetric stretching vibrations observed, due to the reduced tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong IR bands around 800 cm−1 are attributed to water librational modes. The spectra of the three minerals display similarities due to their compositions and crystal structures, but sufficient subtle differences exist for the spectra to be useful in distinguishing the species.


Author(s):  
Haruki Sugiyama

The crystal structures of two salt crystals of 2,2-bis(4-methylphenyl)hexafluoropropane (Bmphfp) with amines, namely, dipyridinium 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoate 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoic acid, 2C5H6N+·C17H8F6O4 2−·C17H10F6O4, (1), and a monohydrated ethylenediammonium salt ethane-1,2-diaminium 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoate monohydrate, C2H10N2 2+·C17H8F6O4 2−·H2O, (2), are reported. Compounds 1 and 2 crystallize, respectively, in space group P21/c with Z′ = 2 and in space group Pbca with Z′ = 1. The crystals of compound 1 contain neutral and anionic Bmphfp molecules, and form a one-dimensional hydrogen-bonded chain motif. The crystals of compound 2 contain anionic Bmphfp molecules, which form a complex three-dimensional hydrogen-bonded network with the ethylenediamine and water molecules.


1987 ◽  
Vol 65 (5) ◽  
pp. 1042-1046 ◽  
Author(s):  
Beverly R. Vincent ◽  
Katherine N. Robertson ◽  
T. Stanley Cameron ◽  
Osvald Knop

The yellow (CH3NH3)4PbI6•2H2O(P21/n, a = 10.421(3) Å, b = 11.334(2) Å, c = 10.668(2) Å, β = 91.73(2)°, Z = 2) contains isolated PbI64− octahedra, CH3NH3+ cations of two types and H2O molecules. The cations and the water molecules are hydrogen-bonded to form [Formula: see text] units arranged in centrosymmtric [Formula: see text] pairs; the centres of these composite units and the Pb atoms form a distorted NaCl-type lattice. The Pb—I bond lengths in the PbI64− anions are compared with those in [Pb(II)I6]ε complexes containing shared I atoms and the effect of the sharing on the bond lengths is discussed. A scheme is proposed for the extensive three-dimensional hydrogen bonding in the structure.


2007 ◽  
Vol 62 (4) ◽  
pp. 491-494 ◽  
Author(s):  
Ji-Xiang Dai ◽  
Fang-Hui Wu ◽  
Wen-Rui Yao ◽  
Qian-Feng Zhang

A hydrogen-bonded chloride-hydrate assembly {[(H2O)4Cl2]2−}∞ has been ion-countered by the complex cations [Fe([9]aneS3)2]2+ ([9]aneS3 = 1,4,7-trithiacyclononane). In {[(H2O)4Cl2]2−}∞, four water molecules and two chloride ions are self-assembled to form a one-dimensional supramolecular array of O-H···O and O-H···Cl hydrogen bonding, which consists of fused fourand six-membered rings. The discrete cation [Fe([9]aneS3)2]2+ has a nearly regular octahedral FeS6 core with an average Fe-S bond length of 2.2586(5) Å .


Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3666
Author(s):  
Liu ◽  
Zhang ◽  
Huang ◽  
Wu ◽  
Ouyang

The effects of hydrogen bonds on the molecular structure of water-tetrahydrofuran (H2O–THF), water-dimethyl sulfoxide (H2O–DMSO), and water-tetrahydrofuran-dimethyl sulfoxide (H2O–THF–DMSO) in binary aqueous solutions and ternary aqueous solutions were studied using Raman spectroscopy. The results indicate that in the binary aqueous solution, the addition of THF and DMSO will generate hydrogen bonds with water molecules, resulting in changes in the peak positions of S=O bonds and C–O bonds. Compared with the binary aqueous solutions, the hydrogen bonds between DMSO and THF, and the hydrogen bonds between DMSO and H2O in the ternary aqueous solutions are competitive, and the hydrogen bond competition is susceptible to water content. In addition, the formation of hydrogen bonds will destroy the fully hydrogen-bonded water and make it change to the partially hydrogen-bonded water. By fitting the spectra into the three Gaussian components assigned to water molecules with different hydrogen bonding (HB) environments, these spectral features are interpreted by a mechanism that H2O in different solution systems has equal types of water molecules with similar HB degrees-fully hydrogen-bonded H2O (FHW) and partially hydrogen-bonded H2O (PHW). The ratio of the intensity transition from FHW to PHW is determined based on Gaussian fitting. Therefore, the variation of hydrogen bond competition can be supplemented by the intensity ratio of PHW/FHW ((IC2 + IC3)/IC1). This study provides an experimental basis for enriching the hydrogen bonding theory of multivariate aqueous solution systems.


2000 ◽  
Vol 56 (4) ◽  
pp. 577-583 ◽  
Author(s):  
Mark. T. Weller ◽  
Mark E. Light ◽  
Thomas Gelbrich

The structure of uranium oxide dihydrate, also known as meta-schoepite (UO2)4O(OH)6·5H2O, has been determined from a synthetic single crystal. The structure, at 150 K, space group Pbcn, lattice constants a = 14.6861 (4), b = 13.9799 (3) and c = 16.7063 (5) Å, consists of layers of stoichiometry (UO2)4O(OH)6, formed from edge-sharing UO7 pentagonal bipyramids, interleaved with hydrogen-bonded water molecules. Three of the layer hydroxyl groups are linked through hydrogen bonding to single water molecules and the three remaining OH units form interactions with water molecules that each act as acceptors in two hydrogen bonds. One of the water molecules in the inter-layer region is disordered over two symmetry-related sites and forms hydrogen-bonded interactions only within the layer and with the uranyl O atoms. The relationship of the structure of meta-schoepite to that of schoepite is discussed in detail.


2013 ◽  
Vol 69 (12) ◽  
pp. 1545-1548 ◽  
Author(s):  
De-Hong Wu

The title compound, 3C6H4N4O2S2·2C3H7NO·4H2O, comprises three 2,2′-disulfanylidene-5,5′-biimidazolidinylidene-4,4′-dione molecules, two dimethylformamide molecules and four water molecules arranged around a crystallographic inversion centre. The non-H atoms within the 5,5′-biimidazolidinylidene molecule are coplanar and these molecules aggregate through N—H...S hydrogen-bonding interactions with cyclic motifs [graph setR22(8)], giving two-dimensional ribbon structures which are close to being parallel. The two independent water molecules associate to form centrosymmetric cyclic hydrogen-bonded (H2O)4tetrameric units [graph setR44(8)]. The ribbon structures extend along theaaxis and are linked through the water tetramers and the dimethylformamide molecules by a combination of two- and three-centre hydrogen bonds, giving an overall three-dimensional structure.


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