Independent Water Molecules Research Articles

Nitrosodisulphonates and hydroxylamine-N,N-disulphonates. V. A potassium salt of hydroxylamine-N,N-disulphonic acid with a displacive superlattice structure

The structure of the potassium salt of hydroxylamine-N,N-disulphonate, with the formula K5HN2S4O14•H2O, has been determined by X-ray diffraction. The crystals are triclinic, a = 14.011(6), b = 16.118(9), c = 11.867(6) Å, α = 103.28(6), β = 106.76(3), γ = 86.38(3)°, [Formula: see text] with Z = 6. The integrated intensities of 8694 independent reflections were measured on a four-circle diffractometer, 5236 of which were used in the refinement to give a final least-squares weighted residual of 0.107 and a conventional R factor of 0.081.The structure forms a six-fold derivative lattice, which arises by small displacements (ca. 0.2 Å) of the atom positions from an average structure which is triclinic with Z = 1. This results in three very short H bonds, average length 2.46 Å, which link the three independent anion-dimers, being symmetry-free in this structure. Other bond lengths and angles in the anions are very similar to those in the Rb salt. The K+ ions show 8, 9, and 10 coordination, in a number of different polyhedral types. The three independent water molecules are each coordinated to three totally distinct K+ ions, and are linked to the anions by weak H bonds. The structural complexity may be explained in terms of a Lewis acid–base "mismatch" of the cations and anions present.

Synthesis, characterization and crystal structure of the anilinium β-octamolybdate dihydrate

The anilinium β-octamolybdate dihydrate has been prepared in acidic aqueous solution. TG, DTG, IR and 1H NMR techniques have been used to identify the compound. It belongs to a series of molybdates of alkyl-N- and -N,N-substituted anilinium cations. Single crystals have been analyzed by X-ray diffraction. Crystal data are: (C 6H 8N) 4[Mo 8O 26] · 2H 2O, space group P 1 , Z = 1, a = 10.007(1), b = 8.014(2), c = 14.645(8)Å, α = 109.81(3), β = 108.59(2), γ = 85.44(2)°, V = 1052.9(6) Å 3, D o = 2.49(1), D x = 2.52 mg m −3, R = 0.026 and R w = 0.031 for 5297 observed reflexions. The crystal structure consists of discrete [β-Mo 8O 26] 4− polyanions, two crystallographically independent (C 6H 8N) + cations and one independent water molecule. Polyanions are linked to the cations and to the water molecules by hydrogen bonds of types NH…O and OH…O.

Neutron diffraction study of sodium hydrogen maleate trihydrate, NaH[C4H2O4].3H2O, at 120 K

M r = 192.10, triclinic, P1, a = 5.927 (2), b=6.288(2), c= 11.222(4)A, it= 104.00(2), /~= 91.47 (2), ~,= 100.26 (2) ° , V= 398.3 (3)/k 3, Z= 2, D x = 1.60 (2) g cm -3, 2 = 0.8323 (4)/~, /t = 1.62 (5) cm -1, F(000) = 118, T= 120 (1.5) K. Final R = 0.033 for 2508 independent reflexions. The hydro- gen maleate ion forms a close to planar ring structure containing a short but still very asymmetric hydrogen bond: O...O - 2.445 (1), O-H = 1.079 (2) and H...O = 1.367 (2)/k. The three water molecules are crystaUographically independent, each with a distorted tetrahedral environment. A comparison is made with intramolecular hydrogen-bond schemes in other hydro- gen maleates. Introduction. In the current hydrogen-bond project an emphasis is presently laid on detailed studies of geometry and electron density of strong hydrogen bonds and of water molecules in different crystal environments. Nail maleate.3H20 would appear a particularly suitable choice as it contains a strong hydrogen bond, on which no crystallographic sym- metry restrictions are imposed, as well as three independent water molecules. Furthermore, for the purposes of electron-density studies, it has the advan- tage that it is centrosymmetric (P1) and contains only light elements. X-ray diffraction studies of the title compound at room temperature by Weissenberg film methods have been reported briefly by Gupta, Prasad & Yadav (1972) and by Gupta & Yadav (1974). The prime purpose of the present neutron diffraction work at 120 K has been to study the detailed geometry of the short intramolecular hydrogen bond and to obtain accurate thermal parameters and hydrogen positions for a subsequent electron density study using the X-N technique. * Hydrogen-Bond Studies. 146. Part 145: Hermansson & Lunell (1982). Experimental. Crystal growth: Nail maleate.3H20 prepared from sodium hydroxide and maleic acid; recrystallized several times from aqueous solution. Single crystals grown by slow evaporation of a saturated aqueous solution at room temperature. A crystal of volume 15 mm a (polyhedron --,1.6 × 2.9 x 4.5 mm) was mounted on an aluminium pin and covered with polystyrene film by dipping in chloroform solution to prevent water loss. Crystal data: Cell dimensions determined at 120 K from single-crystal X-ray diffraction data (Olovsson, Kvick & Olovsson, 1984). Linear absorption coeffi- cient determined experimentally by measuring the attenuation of a narrow beam of neutrons through different Nail maleate.3H20 crystals. From the coefficients for true absorption for Na, H, C and O (corrected to our wavelength, 0.8323 (4),~) and the incoherent scattering cross-sections for Na, C and O as tabulated in International Tables for X-ray Crystal- lography (1968, 1974), a value of 36 (1) × 102 fm 2 was calculated for the mean incoherent scattering cross- section for H. Data collection and reduction: Intensity data col- lected at 120 K on a four-circle diffractometer (D9) at the ILL (Institut Laue-Langevin) High-Flux Reactor in Grenoble. Primary beam monochromatized by a Cu crystal ((200) plane in transmission). Detector: 3He proportional counter. A closed-cycle Displex® system (Model CS-1003, Air Products and Chemicals Inc.) was used for cooling. The crystal was enclosed in a vanadium cylinder which was further surrounded by an evacuated aluminium can. A phase transition in KH2PO 4 at 122.5 K was used to check the tem- perature. A difference of 1.0 K between the thermo- couple and crystal was noted. Temperature generally constant within +1.5 K. Flux at sample 3 ×106 neutrons cm-2s -1 at a wavelength of 0.8323 (4) A. A 0.25 mm erbium foil was placed in front of the monitor to filter out the second-order Q,/2) component in the beam. 0-2t~ step-scan technique, scan interval for the peak 0.6, 0.6, 1.0, 1.5 and 2.4 ° for 0 values 0, 15, 25,

The crystal structure of the spontaneously resolved Λ(R,R)Δ(G,R)-aquo(ethylenediaminetriacetatoacetic acid) cobalt(III) trihydrate, Λ(R,R)Δ(G,R)-[Co(Hedta)H 2O]·3H 2O

Aquo(ethylenediaminetriacetatoacetic acid)cobalt(III) [Co(Hedta)H 2O], prepared from an acidic solution (pH < 1) of K[Co(edta)], has been found to be resolved spontaneously and its crystal structure has been determined by single crystal X-ray diffraction techniques. Crystal data are as follows: Λ(R,R)Δ(G,R)-[Co(C 10H 13N 2O 8)H 2O]·3H 2O, orthorhombic, space group P2 12 12 1, a = 25.880(2) Å, b = 14.669(1) Å, c = 8.453(1) Å, Z = 8, R = 0.054. The spontaneously resolved [Co(Hedta)H 2O]·3H 2O is different in crystal structure from the corresponding complexes of the other metal ions [M(Hedta)H 2O] (M = Rh, Fe, Cr, and Ga) crystallized similarly, which are all racemic and isomorphous. The crystal lattice is composed of two crystallographically independent complexes and water molecules. The uncoordinated protonated acetate group (−CH 2COOH) has the same conformation in the two independent complexes. This conformation is also found in other [M(Hedta)H 2O] complexes. Each uncoordinated −CH 2COOH arm is involved in hydrogen bonding with one molecule of water crystallization. The complexes are linked with one another through the intermolecular hydrogen bonding between the coordinated water molecule and the uncoordinated oxygen atom, forming ring-handed pseudo-4 1 spiral chains along the twofold screw axes parallel to the a axis. By comparison of these homochiral spiral chains with the corresponding 2 1 chains found in the other metal complexes, [M(Hedta)H 2O], formed by the hydrogen bonding similar to the pseudo-4 1 chains in [Co(Hedta)H 2O]·3H 2O, the characteristic packing mode in the title compound can be evaluated.

The crystal structures of 1,5,12,16,23,26,29,32,35-nonaoxa[13][5.5]orthocyclophane and its complex with rubidium picrate

The crystal structures of the macrobicyclic polyether (Ic) systematically named in the title, and of its complex with rubidium picrate have been determined from observations collected on a CAD4 diffractometer. Crystals of the uncomplexed ether are monoclinic with four molecules in a unit cell having a= 8.859(4), b= 11.555(10), c= 25.325(11)A and β= 102.49(4)° and space group P21/c. The structure was solved by direct methods and refined by full matrix least squares to R 0.068 for 3 285 observed reflections. The molecules take up a folded conformation, with the aliphatic bridge much nearer one benzene ring than the other. There are several unexpected values for the torsion angles. The rubidium picrate complex is triclinic with space group P. In the unit cell a= 16.280(4), b= 16.660(5), c= 16.077(3)A, α= 111.62(2), β= 116.29(2), γ= 91.32(2)°, there are two crystallographically independent rubidium ions, ligand molecules (Ic), picrate ions, and water molecules. One rubidium, Rb(1), is nine-co-ordinated by the oxygen atoms of (Ic)(1) with Rb–O ranging from 2.952(7) to 3.368(11)A, giving a complex cation [Rb(1)(Ic)(1)]+. The second rubidium, Rb(2), is eleven-co-ordinated by the nine oxygen atoms of (Ic)(2)[Rb–O 2.922(11)–3.277(15)A], by a nitro-oxygen atom from picrate (2)[Rb–O 2.933(16)A], and by a water molecule on a centre of symmetry [Rb–O 3.077(2)A]. This water molecule bridges two complexed ion pairs so that the entity is {[Rb(2)(Ic)(2)picrate(2)]2H2O}0. There may be hydrogen bonding contacts between the second water molecule, the co-ordinating picrate(2) and the unco-ordinated picrate(1). Disorder is evident in the aliphatic chains of each ligand and in the picrate(1). Least squares refinement in two blocks of full matrices gave R 0.105 for 4 746 observed reflections. The conformations of the complexed forms of the macrobicyclic molecule are similar and differ markedly from that of the uncomplexed molecule.

Hydrogen bond studies. CXXXVIII. Neutron diffraction studies of LiNO3.3H2O at 120 and 295 K

For pt.CXXXVII see ibid., vol.B35, p.2384 (1979). LiNO 3.3H 2O has been studied by neutron diffraction at 120 and 295 K. The final R(w.F 2) values are 4.5% (120K) and 4.9% (295K). The crystal structure found in a previous room-temperature X-ray study is confirmed: one water molecule is involved in six hydrogen bonds; the other independent water molecule in the structure has a tetrahedral environment comprising two Li + ions and two medium-strong hydrogen bonds. The four different O...O hydrogen-bond lengths increase by 0.02-0.03 Aring going from 120 to 295K. The mean-square amplitudes of vibration for the N and O atoms are found to be closely proportional to temperature. For the H and Li atoms the vibrational amplitudes are less sensitive to temperature. Crystal data: space group Cmcm, Z=4; at 120K a=6.713 (7), b=12.669 (4), c=5.968 (5) Aring; at 295K a=6.8018 (4), b=12.7132 (9), c=5.9990 (4) Aring.

A neutron diffraction study of the diaquohydronium ion in yttrium oxalate trihydrate

Five structures of yttrium oxalate trihydrate and its deuterated isomorphs have been determined from least-squares refinement of neutron diffraction data. Three structures with different H–D isotopic ratios were determined from 25 °C data and two structures with the same isotopic ratios were determined from data collected at 60 and −155 °C. The cell dimensions for the structures are as follows: YHOX 25 °C, a0 = 8.6962(6) Å, c0 = 12.824(3) Å YDOX 25 °C, a0 = 8.6989(7) Å, c0 = 12.818(3) Å YHDOX 25 °C, a0 = 8.704(2) Å, c0 = 12.832(2) Å YHDOX 60 °C, a0 = 8.708(2) Å, c0 = 6.435(3) Å YHDOX −155 °C, a0 = 8.677(4) Å, c0 = 12.751(7) Å. In each of the structures a proton or deuteron is on a twofold symmetry axis and nearly centered between two H2O molecules forming an H5O2 ion. The O–H–O bond is symmetrical but not linear; the z parameters for H and O are slightly different. The O–H–O distance in the diaquo ion is 2.442(2) Å, and the O–D–O distance is 2.454(2) Å. The four other protons in the diaquo ion (paired by symmetry) form nonlinear hydrogen bonds with O atoms in the oxalate molecules [2.643(2) and 2.680(2) Å]. The respective O–H–O angles are 178.2(3) ° and 167.9(3) °. There is a nonequilibrium temperature dependence of the partitioning of hydrogen and deuterium among the available proton positions. The centered proton in the H5O2 is the preferred site for hydrogen and the H/D ratio increases with decreasing temperature. Between 155 and 25 °C the structure of YH(C2O4)2⋅3H2O becomes progressively disordered with respect to the H5O2+ ion. At approximately 53 °C, there is a dimorphic transition in the structure and both the independent water molecule and the diaquo ion become disordered and the space group changes from P42/n to P4/n; c0 is halved. The progressive disorder is superimposed upon the P4/n disorder.