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 XIV. Hydrogen bonding and orientation of the ammonium ion in fluorides, with observations on the transition temperatures in cubic cryolite, elpasolite, and perovskite halides

1985 ◽  
Vol 63 (12) ◽  
pp. 3328-3353 ◽  
Author(s):  
Osvald Knop ◽  
Wolfgang J. Westerhaus ◽  
Michael Falk ◽  
Werner Massa
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Halogen Atom ◽  
Ammonium Ion ◽  
Transition Temperatures ◽  
Coordination Numbers ◽  
Geometric Tolerance ◽  
Ionic Size

The ir spectra of the isotopic probe ion NH3D+ have been used to obtain information about the symmetry, orientation, and hydrogen-bonding involvement of the ammonium ion, between 10 K and room temperature, in NH4F, NH4HF2, (NH4)2[Cr(H2O)6]F5, NH4PF6, (NH4)3SiF7, the elpasolites (NH4)2BFeF6 (B = Na, K) and CS2NH4MF6 (M = Fe, Al), and the cryolites (NH4)3MF6 (M = Al, Cr, Fe). Several of these fluorides exhibit low-temperature transitions, some of which are evident in the probe-ion spectra. It is shown that relating the isotopically isolated ND stretching and bending frequencies to the [Formula: see text] distances and to the coordination numbers of the ammonium ion reveals important trends in the dependence of the behaviour of the ion on its immediate environment in the crystal. A detailed discussion is presented of the effect of ionic size and the geometric tolerance factor t on the transition temperatures of cubic cryolite, perovskite, and elpasolite halides, as well as on the anisotropy of the principal thermal amplitudes of the halogen atom in such compounds. The relation between Ttr and the frequency of the ND stretching absorption of NH3D+ in the ammonium representatives of these classes of halides is also explored.

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. 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.

A room-temperature self-healing elastomer with ultra-high strength and toughness fabricated via optimized hierarchical hydrogen-bonding interactions

2022 ◽  
Author(s):  
Liangliang Xia ◽  
Ming Zhou ◽  
Hongjun Tu ◽  
wen Zeng ◽  
xiaoling Yang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Polymeric Materials ◽  
High Strength ◽  
Self Healing ◽  
High Mechanical Strength ◽  
Hydrogen Bonding Interactions ◽  
Healing Efficiency ◽  
Good Healing

The preparation of room-temperature self-healing polymeric materials with good healing efficiency and high mechanical strength is challenging. Two processes are essential to realise the room-temperature self-healing of materials: (a) a...

Infrared spectra of the ammonium ion in crystals. Part VI. Hydrogen bonding in simple and complex ammonium halides

1979 ◽  
Vol 57 (15) ◽  
pp. 2003-2003
Author(s):  
Osvald Knop ◽  
Ian A. Oxton ◽  
Michael Falk
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectra ◽  
Ammonium Ion ◽  
Ammonium Halides

not available

scholarly journals (η6-Benzene)(carbonato-κ2O,O′)[dicyclohexyl(naphthalen-1-ylmethyl)phosphane-κP]ruthenium(II) chloroform trisolvate

2014 ◽  
Vol 70 (7) ◽  
pp. m272-m273
Author(s):  
Saravanan Gowrisankar ◽  
Helfried Neumann ◽  
Anke Spannenberg ◽  
Matthias Beller
Keyword(s):  
Hydrogen Bonding ◽  
Metal Complex ◽  
Room Temperature ◽  
Crystal Packing ◽  
The Other ◽  
Asymmetric Unit ◽  
Carbonate Group ◽  
Acta Cryst ◽  
Hydrogen Bonding Interactions ◽  
Solvent Molecules

The title compound, [Ru(CO3)(η6-C6H6){(C6H11)2P(CH2C10H7)}]·3CHCl3, was synthesized by carbonation of [RuCl2(η6-C6H6){(C6H11)2P(CH2C10H7)}] with NaHCO3in methanol at room temperature. The RuIIatom is surrounded by a benzene ligand, a chelating carbonate group and a phosphane ligand in a piano-stool configuration. The crystal packing is consolidated by C—H...O and C—H...Cl hydrogen-bonding interactions between adjacent metal complexes and between the complexes and the solvent molecules. The asymmetric unit contains one metal complex and three chloroform solvent molecules of which only one was modelled. The estimated diffraction contributions of the other two strongly disordered chloroform solvent molecules were substracted from the observed diffraction data using the SQUEEZE procedure inPLATON[Spek (2009).Acta Cryst.D65, 148–155].

Sign in / Sign up

Export Citation Format

Share Document