Infrared Spectra of the Ammonium Ion in Crystals. I. Ammonium Hexachloroplatinate(IV) and Hexachlorotellurate(IV)

1975 ◽  
Vol 53 (18) ◽  
pp. 2675-2682 ◽  
Author(s):  
Ian A. Oxton ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Infrared Spectra ◽  
Distinct Type ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Bending Vibrations ◽  
Vibrational Coupling

Infrared spectra of polycrystalline (NH4)2PtCl6 and (NH4)2TeCl6 at various degrees of deuteration were recorded between 4000 and 1000 cm−1 at 30 and −165 °C. The stretching and bending vibrations of NH4+, NH3D+, NH2D2+, NHD3+, and ND4+ ions in these two compounds were systematically examined. The observed fundamentals were unambiguously assigned by analogy with the vibrations of the partially deuterated methanes. The spectrum of isotopically dilute NH3D+ confirms the existence of only one crystallographically distinct type of ammonium ion in the structure, on sites of Td symmetry. Vibrational coupling of neighboring ammonium ions was not detected.

Infrared Studies of Water in Crystalline Hydrates: K2CuCl4•2H2O

1974 ◽  
Vol 52 (7) ◽  
pp. 1029-1041 ◽  
Author(s):  
Gwen H. Thomas ◽  
Michael Falk ◽  
Osvald Knop
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Distinct Type ◽  
Vibrational Coupling ◽  
Infrared Studies ◽  
Crystalline Hydrates

Infrared spectra of polycrystalline K2CuCl4•2H2O at different degrees of deuteration were recorded, between 4000 and 300 cm−1, at temperatures from −160 to 90 °C. The spectra confirm the existence of only one crystallographically distinct type of water molecule in the structure, on sites of symmetry C2r. Vibrational coupling of the bending fundamentals of the water molecule has been analyzed in detail. It is shown that the existence and magnitude of such coupling may be used to predict, from the spectrum of a hydrate, the manner in which a water molecule participates in the crystal structure. The structure and the vibrational spectra of K2CuCl4•2H2O are compared with those of the closely related CuCl2•2H2O.

Infrared spectra of the ammonium ion in crystals. Part XII. Low-temperature transitions in ammonium dichromate, (NH4)2Cr2O7

1982 ◽  
Vol 60 (15) ◽  
pp. 1972-1977
Author(s):  
Gábor Keresztury ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Abundance Ratio ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Hydrogen Bonding Interactions ◽  
Wide Range ◽  
Ammonium Dichromate ◽  
The Difference

Examination of the infrared spectra of the probe ions NH3D+ and NHD3+ in ammonium dichromate confirms the existence of the lowest (Ttr ~ 125 K) of the three transitions that are known, from nonspectroscopic evidence, to occur in this crystal below room temperature. Below Ttr the ammonium ions are of two types, in an abundance ratio of 1:1 and both of symmetry C1. Above Ttr the probe ion spectra are difficult to interpret in detail. The strength of the hydrogen-bonding interactions covers a wide range, as indicated by the difference between the highest and the lowest values of the isotopically isolated ND stretching frequencies at 10 K, 2392 and 2234 cm−1.

Infrared spectra of the ammonium ion in crystals. Part IX. Ammonium tetraphenylborate, NH4B(C6H5)4: crystal structure at room temperature and at 120 K, and evidence of hydrogen bonding

1980 ◽  
Vol 58 (13) ◽  
pp. 1355-1364 ◽  
Author(s):  
Wolfgang J. Westerhaus ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Crystal Structure ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Coulombic Interaction ◽  
Phenyl Rings ◽  
Librational Motion ◽  
A Site

A determination of the crystal structure of ammonium tetraphenylborate (ATPB) at 120 K shows that the ammonium ion in this crystal, at a site of symmetry D2d, is oriented in a way consistent with the expectation from a simple model based on Coulombic interaction. Infrared spectra of the isotopic ammonium ions obtained between 10 K and room temperature indicate that the effect of the tetraphenylborate anion on the strength of the N—H bond (as measured by the stretching frequency) is small and independent of temperature, and that the distortion of the ammonium ion from Td symmetry is slight. From the combined evidence it is concluded that the ammonium ion in ATPB must be regarded as hydrogen-bonded, but the potential field due to the four phenyl rings surrounding the ammonium ion offers little resistance to the bending (and probably also to the librational) motion of the ion.

Infrared Spectra of the Ammonium Ion in Crystals. II. The Ammonium Ion in Trigonal Environments, with a Consideration of Hydrogen Bonding

1975 ◽  
Vol 53 (22) ◽  
pp. 3394-3400 ◽  
Author(s):  
Ian A. Oxton ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Infrared Spectra ◽  
Isotopic Dilution ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Dilution Technique ◽  
Intensity Ratios ◽  
Normal Hydrogen ◽  
Trifurcated Hydrogen Bond

Infrared spectra of polycrystalline (NH4)2GeF6, β-(NH4)2SiF6, and (NH4)2Pb(SO4)2 have been recorded at room and liquid-nitrogen temperatures. The N—D stretching and bending fundamentals of the isotopically dilute NH3D+ ion in these compounds have been studied with particular attention. The occurrence of N—D stretching doublets and bending triplets, of approximate intensity ratios 1:3 and 2:3:3 respectively, confirms the C3v symmetry of the ammonium ion and suggests that the isotopic dilution technique will prove useful as a diagnostic tool for ascertaining site symmetries of the ammonium ion. The spectra are consistent with non-rotating ammonium ions. The frequencies of dilute NH3D+ ions suggest that for the ammonium ion in (NH4)2Pb(SO4)2 a trifurcated hydrogen bond is stronger than a normal hydrogen bond.

Infrared spectra of the ammonium ion in crystals. III. The ammonium ion in crystal sites of symmetry S4

1976 ◽  
Vol 54 (6) ◽  
pp. 892-899 ◽  
Author(s):  
Ian A. Oxton ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Liquid Nitrogen ◽  
Infrared Spectra ◽  
Ammonium Ion ◽  
Site Symmetry ◽  
Ammonium Ions ◽  
Ammonium Perrhenate ◽  
Combination Modes

The infrared spectra of the isotopically isolated NH3D+ ion in polycrystalline ammonium perrhenate, NH4ReO4, and ammonium tetrachlorocuprate(II) dihydrate, (NH4)2.CuCl4.2H2O, have been recorded at room and liquid-nitrogen temperatures. In the crystals of both compounds the ammonium ions are located at sites of S4 symmetry. The N—D stretching mode of NH3D+ in NH4ReO4 is a singlet, as expected for this site symmetry. In (NH4)2.CuCl4.2H2O, however, a doublet is observed which reveals the occurrence of two non-equivalent orientations of the ammonium ion. The spectra of the undeuterated compounds contain bands due to combination modes involving the librations of the ammonium ion. This shows that the ions are non-rotating.

Infrared spectra of the ammonium ion in crystals. Part VIII. Spectroscopic criteria of highly-bent hydrogen bonds

1980 ◽  
Vol 58 (9) ◽  
pp. 867-874 ◽  
Author(s):  
Osvald Knop ◽  
Wolfgang J. Westerhaus ◽  
Michael Falk
Keyword(s):  
Low Temperature ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Ammonium Ion ◽  
Temperature Transition ◽  
Increasing Temperature

Available evidence suggests that (1) the stretching frequencies of highly-bent hydrogen bonds decrease with increasing temperature, regardless of whether the bonds are static or dynamic in character, to a single acceptor or to several competing acceptors; and (2) departures from symmetric trifurcation (or bifurcation) toward asymmetric situations lower the stretching frequency. In further support of these criteria isotopic probe ion spectra between 10 K and room temperature have been obtained for taurine and for trigonal (NH4)2MF6 (M = Si, Ge, Sn, Ti). Evidence of a low-temperature transition at 100(10) K in trigonal (NH4)2SnF6 is presented, and existence of the previously reported transition at 38.6 K in trigonal (NH4)2SiF6 is confirmed. Symmetry changes associated with these transitions are discussed.

scholarly journals Molecular recognition of organic ammonium ions in solution using synthetic receptors

2010 ◽  
Vol 6 ◽  
Author(s):  
Andreas Späth ◽  
Burkhard König
Keyword(s):  
Molecular Recognition ◽  
Hydrophobic Interactions ◽  
Covalent Bond ◽  
Ammonium Ion ◽  
Synthetic Receptors ◽  
Ammonium Ions ◽  
Wide Range ◽  
Covalent Bond Formation ◽  
Reversible Covalent ◽  
Ion Receptors

Ammonium ions are ubiquitous in chemistry and molecular biology. Considerable efforts have been undertaken to develop synthetic receptors for their selective molecular recognition. The type of host compounds for organic ammonium ion binding span a wide range from crown ethers to calixarenes to metal complexes. Typical intermolecular interactions are hydrogen bonds, electrostatic and cation–π interactions, hydrophobic interactions or reversible covalent bond formation. In this review we discuss the different classes of synthetic receptors for organic ammonium ion recognition and illustrate the scope and limitations of each class with selected examples from the recent literature. The molecular recognition of ammonium ions in amino acids is included and the enantioselective binding of chiral ammonium ions by synthetic receptors is also covered. In our conclusion we compare the strengths and weaknesses of the different types of ammonium ion receptors which may help to select the best approach for specific applications.

Orally Ingested Microencapsulated Urease and an Adsorbent, Zirconium Phosphate, to Remove Urea in Kidney Failure

1987 ◽  
Vol 10 (4) ◽  
pp. 269-274 ◽  
Author(s):  
E.A. Wolfe ◽  
T.M.S. Chang
Keyword(s):  
Renal Function ◽  
Zirconium Phosphate ◽  
Intestinal Tract ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Dialysis Therapy ◽  
Dialysis Treatment ◽  
In Series ◽  
Removal System

Dialysis is the conventional treatment for chronic renal failure. It is cumbersome, expensive and time-consuming and thus alternate treatments have long been sought. A compact system consisting of haemoperfusion in series with ultrafiltration can nearly replace dialysis. A urea removal system is the only step required to complete this approach. The potential of combining a microencapsulated enzyme, urease, with an ammonium ion adsorbent, zirconium phosphate, to remove urea was examined in vitro. Urease converts urea to ammonium ions which are then adsorbed on-to zirconium phosphate. This combination would be most effective in the intestinal tract. The capacity of zirconium phosphate is probably not enough to effect the removal of enough urea to completely replace dialysis in patients with no renal function. However, this system could potentially 1) delay the onset of dialysis therapy in patients who still have some renal function, either alone or in combination with haemoperfusion-ultrafiltration, or 2) reduce dialysis treatment times.

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