Hydrolysis of [PtCl] in Concentrated NaOH Solutions.

The transformations of Pt complex species in concentrated NaOH solutions (1-12 M) of Na[PtCl] were studied with a combination of methods, including Pt nuclear magnetic resonance, ultraviolet-visible, and Raman spectroscopy. The two-step process was observed under the following conditions: (1) formation of the [Pt(OH)Cl] anion that proceeds relatively fast even at room temperature and (2) further slow substitution of the last chlorido ligand with the formation of the [Pt(OH)] anion. Overall, it was determined that the [PtCl] to [Pt(OH)] transformation (especially the first stage) is greatly accelerated under blue light (455 nm) irradiation.

Hydrogen Bonds: Raman Spectroscopic Study.

The work outlines general ideas on how the frequency and the intensity of proton vibrations of X-H···Y hydrogen bonding are formed as the bond evolves from weak to maximally strong bonding. For this purpose, the Raman spectra of different chemical compounds with moderate, strong, and extremely strong hydrogen bonds were obtained in the temperature region of 5 K-300 K. The dependence of the proton vibrational frequency is schematically presented as a function of the rigidity of O-H···O bonding.

Oxochloroselenate(IV) with Incorporated {Cl }: The Case of Strong Cl⋅⋅⋅Cl Halogen Bonding.

Reaction of SeO , tetramethylammonium (TMA) chloride, aqueous HCl and Cl yields oxochloroselenate with incorporated Cl units, TMA {[Se O Cl ](Cl )}. The main feature of this compound is the strong (up to 3.5 kcal mol , according to DFT calculations) Cl⋅⋅⋅Cl bonding, which is also detected by Raman spectroscopy.

Rule, Not Exclusion: Formation of Dichlorine-Containing Supramolecular Complexes with Chlorometalates(IV).

Supramolecular derivatives of chlorostannate(IV) and -plumbate(IV) with {Cl} units, Cat{[MCl](Cl)} (-; M = Sn, Pb, cat = 1-methylpyridinium (1-MePy), tetramethylammonium (TMA)) were prepared and characterized by X-ray diffractometry and Raman spectroscopy. In particular, the TMA-containing complexes demonstrate remarkable thermal stability, releasing Cl only at elevated temperatures.

One-Dimensional Diiodine-Iodobismuthate(III) Hybrids Cat{[BiI](I)}: Syntheses, Stability, and Optical Properties.

One-dimensional iodine-rich iodobismuthates(III), Cat{[BiI](I)} [Cat = 1,4-MePy () and 1-EtBMAP ()], feature the highest amount of "trapped" diiodine units in polyhalogen-halometalates of p-block elements. Both complexes have narrow optical band gaps (1.55 and 1.

Proton motion inside [(DMF)H][WCl]: structural, Raman and luminescence studies.

Protonation of DMF by (HO)[WCl] results in the appearance of strongly proton coupled [(DMF)H] dimers. Such units are captured as the cationic part of [(DMF)H][WCl] (1). The proton behavior in such dimers was studied for the first time with single crystal X-ray diffraction (XRD) and H MAS NMR, Raman and photoluminescence (PL) spectroscopic techniques.

Photoinduced Deposition of Platinum from (BuN)[Pt(NO)] for a Low Pt-Loading Pt/TiO Hydrogen Photogeneration Catalyst.

An efficient method for the deposition of ionic platinum species PtO onto a TiO surface was developed on the basis of light-induced activation of the [Pt(NO)] anion. The deposited PtO species with an effective Pt oxidation state between +4 and +2 have an oxygen-made environment and include single ion centers {PtO} and polyatomic ensembles {PtO} connected to a TiO surface with Pt-O-Ti bonds. The resulting PtO/TiO materials were tested as photocatalysts for the hydrogen evolution reaction (HER) from a water ethanol mixture and have shown uniquely high activity with the rate of H evolution achieving 11 mol h per gram of Pt, which is the highest result for such materials reported to date.

Opening the Third Century of Polyhalide Chemistry: Thermally Stable Complex with "Trapped" Dichlorine.

Unlike polyhalides of heavier halogens, polychlorides still remain exotic curiosities. Herein, we report preparation and investigation of complexes Cat {[TeCl ](Cl )} (cat=1-methylpyridinium (1) and tetramethylammonium (2)) where dichlorine units are "trapped" by chlorotellurate(IV) anions via a system of non-covalent Cl⋅⋅⋅Cl interactions. Complex 2 reveals a record thermal stability (>100 °C) for inclusion compounds with Cl , indications that such compounds can be used as solid Cl source.

One- and Two-Dimensional Iodine-Rich Iodobismuthate(III) Complexes: Structure, Optical Properties, and Features of Halogen Bonding in the Solid State.

Reactions of BiI, I, and iodide salts of two different pyridinum cations result in the formation of the novel iodine-rich iodobismuthates(III) (1,3-MePy){[BiI](I)} () and (1-MePy){[BiI](I)) (), where the halometalate anions are connected by diiodine linkers into one- or two-dimensional supramolecular structures. Both complexes reveal narrow optical band gaps and fairly high thermal stability, favoring their potential use in photovoltaic devices.

Tautomeric Hydrogen Bond in Dimers of Ibuprofen.

The Raman spectra of polycrystalline samples of ( RS)-2-(4-isobutylphenyl)-propionic acid of the common name ibuprofen have been measured in the temperature range 5-300 K. In the low-frequency spectrum of the normal CH(COOH) and deuterated CH(COOD) species, modes with ∼103 and ∼95 cm wavenumbers were detected, which corresponded to translational vibrations of O-H(D)···O hydrogen bonds of two different tautomers: left L and right R , respectively. At temperatures below 150 K, only the L-tautomer is found, and at T ≥ 150 K, both tautomers are observed.

Raman spectra of crystalline secondary amides.

We present a Raman-spectroscopic study of secondary amides (acetanilide, methacetin, phenacetine, orthorhombic and monoclinic polymorphs of paracetamol) as well as simple amides formanilide and benzanilide. The study was carried out on single crystals and in the temperature range of 5-300K. The series of compounds with the same molecular fragment - acetamide group - can serve as a model system to study the interrelation between this group and the properties of the intermolecular "peptide-type" NH⋯OC hydrogen bonds.

Unusual behavior of benzoic acid at low temperature: Raman spectroscopic study.

The Raman spectra of benzoic acid single crystals have been measured in the temperature range of 5-300K. At T<60K the spectra show at least two anomalous features, one of which is of direct relevance to intensity changes of the lattice modes in the low-wavenumber region. The intensity of modes at ∼86 and ∼146cm(-1) tends to zero at T→0K.

High proton conductivity and spectroscopic investigations of metal-organic framework materials impregnated by strong acids.

Strong toluenesulfonic and triflic acids were incorporated into a MIL-101 chromium(III) terephthalate coordination framework, producing hybrid proton-conducting solid electrolytes. These acid@MIL hybrid materials possess stable crystalline structures that do not deteriorate during multiple measurements or prolonged heating. Particularly, the triflic-containing compound demonstrates the highest 0.

Polymorphism of paracetamol: a new understanding of molecular flexibility through local methyl dynamics.

This study focuses on the interplay of molecular flexibility and hydrogen bonding manifested in the monoclinic (form I) and orthorhombic (form II) polymorphs of paracetamol. By means of incoherent inelastic neutron scattering and density functional theory calculations, the relaxation processes related to the methyl side-group reorientation were analyzed in detail. Our computational study demonstrates the importance of considering quantum effects to explain how methyl reorientations and subtle conformational changes of the molecule are intertwined.

An interpretation of the "anomalous" changes in the low-wavenumber range of the Raman spectra of L-alanine crystals.

"Anomalous changes" in the temperature- and pressure- dependences of the intensities and wavenumbers of the two low-wavenumber modes in Raman spectra of single-crystals of L-alanine have been interpreted in terms of a change in relative contributions of stretching and deformational components into the intermolecular vibrational bands. The relative contributions of the two components into a lattice vibration result from a change of relative orientations of molecules linked by hydrogen bonds in a three-dimensional network on variations of temperature or pressure.

Low-temperature phase transition in glycine-glutaric acid co-crystals studied by single-crystal X-ray diffraction, Raman spectroscopy and differential scanning calorimetry.

The occurrence of a first-order reversible phase transition in glycine-glutaric acid co-crystals at 220-230 K has been confirmed by three different techniques - single-crystal X-ray diffraction, polarized Raman spectroscopy and differential scanning calorimetry. The most interesting feature of this phase transition is that every second glutaric acid molecule changes its conformation, and this fact results in the space-group symmetry change from P2(1)/c to P1. The topology of the hydrogen-bonded motifs remains almost the same and hydrogen bonds do not switch to other atoms, although the hydrogen bond lengths do change and some of the bonds become inequivalent.

Effect of pressure on crystalline L- and DL-serine: revisited by a combined single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy study.

Information on the effect of pressure on hydrogen bonds, which could be derived from single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy, has been compared. L-Serine and DL-serine were selected for this case study. The role of hydrogen bonds in pressure-induced phase transitions in the first system and in the structural stability of the second one are discussed.

Dynamics of the intermolecular hydrogen bonds in the polymorphs of paracetamol in relation to crystal packing and conformational transitions: a variable-temperature polarized Raman spectroscopy study.

The properties of the intermolecular hydrogen bonds in the monoclinic (Form I) and the orthorhombic (Form II) polymorphs of paracetamol, C(8)H(9)NO(2), have been studied by single crystal polarized Raman spectroscopy (40 to 3700 cm(-1)) in a wide temperature range (5 K < T < 300 K) in relation to the dynamics of methyl-groups of the two forms. A detailed analysis of the temperature dependence of the wavenumbers, bandwidths and integral intensities of the spectral bands has revealed an essential difference between the two polymorphs in the strength and ordering of OH···O and NH···O hydrogen bonds. The compression of intermolecular hydrogen bonds is interrelated with crystal packing and the dynamics of methyl-groups.

Monitoring selected hydrogen bonds in crystal hydrates of amino acid salts: combining variable-temperature single-crystal X-ray diffraction and polarized Raman spectroscopy.

Predicting behaviour of hydrogen bonds with varying temperature, in particular-correlating donor-acceptor distances in the O-H···O hydrogen bonds with the frequencies of O-H stretching vibrations is important for understanding dynamics of biomolecules and phase transitions in crystals. A commonly used correlation suggested earlier in the literature is based on statistical analysis of different compounds [A. Novak, Structure and Bonding, 1974, 18, 177; K.

Phase transitions in the crystals of L- and DL-cysteine on cooling: the role of the hydrogen-bond distortions and the side-chain motions. 2. DL-cysteine.

Structural strain and a first-order phase transition in the crystalline DL-cysteine on cooling and on reverse heating were followed by Raman spectroscopy and X-ray diffraction. The transition is reversible and has a large hysteresis (over 100 K). The temperature at which the transition is observed depends strongly on the cooling/heating rate.

Phase transitions in the crystals of L- and DL-cysteine on cooling: intermolecular hydrogen bonds distortions and the side-chain motions of thiol-groups. 1. L-cysteine.

The role of the distortion of the hydrogen bond network and of the motions of the -CH 2SH side chains in the phase transition in the orthorhombic L-cysteine ( (+)NH 3-CH(CH 2SH)-COO (-)) on cooling and the reverse transformation on heating is discussed. The extended character of the phase transition, which was recently discovered by adiabatic calorimetry [ J. Phys.

Investigation of hydrate formation in the system H2-CH4-H2O at a pressure up to 250 MPa.

Phase equilibria in the system H2-CH4-H2O are investigated by means of differential thermal analysis within hydrogen concentration range 0-70 mol % and at a pressure up to 250 MPa. All the experiments were carried out under the conditions of gas excess. With an increase in hydrogen concentration in the initial gas mixture, decomposition temperature of the formed hydrates decreased.

Zr(IV)-monosubstituted Keggin-type dimeric polyoxometalates: synthesis, characterization, catalysis of H2O2-based oxidations, and theoretical study.

The previously unknown Zr(IV)-monosubstituted Keggin-type polyoxometalates (Zr-POMs), (n-Bu4N)7H[{PW11O39Zr(mu-OH)}2] (1), (n-Bu4N)8[{PW11O39Zr(mu-OH)}2] (2), and (n-Bu4N)9[{PW11O39Zr}2(mu-OH)(mu-O)] (3) differing in their protonation state, have been prepared starting from heteropolyacid H5PW11ZrO40.14H2O. The compounds were characterized by elemental analysis, potentiometric titration, X-ray single-crystal structure, and IR, Raman, and 31P and 183W NMR spectroscopy.