Synthesis and Crystal Structures of [(Nicotinic Acid)2H]+I-, [(2-Amino-6-methylpyridine)H]+(NO3)-, and the 1:1 Complex Between 1-Isoquinoline Carboxylic Acid (Zwitter Ion) and L-Ascorbic Acid Assembled via Hydrogen Bonds

Summary. Three new complexes, namely [(nicotinic acid)₂H]⁺I^–, [(2-amino-6-methylpyridine)H]⁺ (NO₃)^–, and the 1:1 complex between 1-isoquinoline carboxylic acid (zwitter ion form) and L-ascorbic acid were synthesized. The IR spectra revealed different types of hydrogen bonds in these compounds. The X-ray structure determination has shown the first compound to consist of a packing of [(nicotinic acid)₂H]⁺ cations and I^– anions. In the dimeric cation the two nicotinic acid molecules (zwitter ions) are connected through hydrogen bonds (O–HO). Each dimer is further engaged in other hydrogen bonds with adjacent dimers giving 2D layers. The I^– ion is located at the inversion center. In the second compound the cation and anion are connected via hydrogen bonds formed between oxygen atoms of the NO₃ ^– anion and NH and NH₂ of the cation generating a layer structure. All atoms are coplanar on mirror planes. In the 1:1 complex the two molecules are connected through hydrogen bonds formed between the two oxygen atoms of the carboxylate group of 1-isoquinoline carboxylic acid (zwitter ion) and the oxygen atoms of the two adjacent hydrogen groups of the L-ascorbic acid molecule. These complex molecules are engaged in other hydrogen bonds with each other forming a 2D system normal to the long b-axis of the unit cell.     

Synthesis and Crystal Structures of [(Nicotinic Acid)2H]+I-, [(2-Amino-6-methylpyridine)H]+(NO3)-, and the 1:1 Complex Between 1-Isoquinoline Carboxylic Acid (Zwitter Ion) and L-Ascorbic Acid Assembled via Hydrogen Bonds

Three new complexes, namely [(nicotinic acid)₂H]⁺I^–, [(2-amino-6-methylpyridine)H]⁺ (NO₃)^–, and the 1:1 complex between 1-isoquinoline carboxylic acid (zwitter ion form) and L-ascorbic acid were synthesized. The IR spectra revealed different types of hydrogen bonds in these compounds. The X-ray structure determination has shown the first compound to consist of a packing of [(nicotinic acid)₂H]⁺ cations and I^– anions. In the dimeric cation the two nicotinic acid molecules (zwitter ions) are connected through hydrogen bonds (O–HO). Each dimer is further engaged in other hydrogen bonds with adjacent dimers giving 2D layers. The I^– ion is located at the inversion center. In the second compound the cation and anion are connected via hydrogen bonds formed between oxygen atoms of the NO₃ ^– anion and NH and NH₂ of the cation generating a layer structure. All atoms are coplanar on mirror planes. In the 1:1 complex the two molecules are connected through hydrogen bonds formed between the two oxygen atoms of the carboxylate group of 1-isoquinoline carboxylic acid (zwitter ion) and the oxygen atoms of the two adjacent hydrogen groups of the L-ascorbic acid molecule. These complex molecules are engaged in other hydrogen bonds with each other forming a 2D system normal to the long b-axis of the unit cell.     

Hydrolysis of the Borohydride Anion BH4−: A 11B NMR Study Showing the Formation of Short-Living Reaction Intermediates including BH3OH−

In hydrolysis and electro-oxidation of the borohydride anion BH₄⁻, key reactions in the field of energy, one critical short-living intermediate is BH₃OH⁻. When water was used as both solvent and reactant, only BH₃OH⁻ is detected by ¹¹B NMR. By moving away from such conditions and using DMF as solvent and water as reactant in excess, four ¹¹B NMR quartets were observed. These signals were due to BH₃-based intermediates as suggested by theoretical calculations; they were DMF·BH₃, BH₃OH⁻, and B₂H₇⁻ (i.e., [H₃B−H−BH₃]⁻ or [H₄B−BH₃]⁻). Our results shed light on the importance of BH₃ stemming from BH₄⁻ and on its capacity as Lewis acid to interact with Lewis bases such as DMF, OH⁻, and BH₄⁻. These findings are important for a better understanding at the molecular level of hydrolysis of BH₄⁻ and production of impurities in boranes synthesis.     

Internal rotation and phase transitions in lanthanum tetrahydroborates

Conclusion The investigation carried out shows that in the low-symmetry compouds La(BH₄)₃ and La(BH₄)₃·3THF, as in the high-symmetry MBH₄, phase transitions occur. An unexpected result is the fact that the symmetry of the environment of the boron ions for these phase transitions practically does not change and remains close to cubic. The activation energy for reorientation of the BH _– ⁴ ion (1.2 kcal/mole) is somewhat overstimated, if we start from the difference in the electronegativity of the boron and hydrogen ions (2.0 and 2.15). This may mean that the nature of the barrier to reorientation of the BH _– ⁴ anion in lanthanum tetrahydroborates is connected with the van der Waals interaction of the tetrahedral BH _– ⁴ groups with the environment. From the¹³⁹La NMR data it follows that the coordination sphere of the triply-charged lanthanum is characterized by low-symmetry of the arrangement of the BH_4– and THF (OC₄H₈) ligands, and the La³⁺-(BH₄)^– bond has predominantly ionic character. Consequently, the potential energy of the BH _– ⁴ anions in the lattice is the sum of the strong isotropic ionic component and the substantially weaker anisotropic van der Waals component. In the low-temperature phases, for both compounds we observe structurally nonequivalent positions for the BH _– ⁴ anions, retained in the high-temperature phase. The phase transitions in the studied compounds are connected with a change in the nature of the hydrogen atom distribution. Due to the low height of the barriers, the reorientational mobility sets in even at low temperatures, and in the phase transition region the value of _c reaches 10¹⁰–10¹¹ Hz. For such a high reorientational frequency, there may be substantial effects from correlation rotation of the anions, leading to a change in the hydrogen atom distribution in the structure and an order-disorder type phase transition.Institute of Inorganic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 1, pp. 69–72, January–February, 1988.     

Anionic zirconium and hafnium borohydride complexes

Zirconium and hafnium tetrachlorides react with NaBH₄, in dimethoxyethane (DME) to give [Na(DME)₃][M(BH₄)₅]. These compounds react with Bu₄NBH₄ and Ph₄PBH₄ to give (R₄E)[M(BH₄)₅]. Bidentate and tridentate BH ₄ ^– occur in [M(BH₄)₅]^– according to IR spectroscopy. Data from¹H and¹H-{¹¹B} NMR spectra are consistent with intermolecular exchange of BH₄ ligands in solutions of complexes (I)–(VI). The BH₄groups and the bridging and terminal protons in each BH₄ group equilibrate rapidly. Heating the complexes (I)–(VI) reduces the central atom, releases diborane, and decomposes the outer-sphere cation. The neutral borohydrides M(BH₄)₄, can be prepared by thermolysis of the sodium salts (I) and (II).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1207–1214, June, 1990.     

Vibrational spectrum and structure of nitrosothiocarbamylcyanomethanide ion

The IR spectra (400–4000 cm^–1) of the sodium salt of the nonlinear nitrosocontaining acido ligand of a methanide type Na[ONC(CN)C(S)NH₂], as well as of the deutero-derivative compound were studied. The frequencies and the forms of the normal vibrations of NaL (the H-form) and NaL (the D form) were calculated in the harmonic approximation of the valence-force field; a theoretical IR spectrum of compound NaL(H) was obtained from the quantum-chemical calculation. The frequencies observed in the spectrum were assigned from the results of the calculation, the force constants of the bonds were analyzed, and were compared with those for the salt of the oxo anion Na[ONC(CN)C(O)NH₂]. Various Cu²⁺ and Ni²⁺ complexes with a thio ligand were synthesized and the type of coordination of the nonlinear anion was established from the IR spectra.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 312–317. May–June, 1988.     

Structure of (BEDT-TTF)-Based Organic Metals with Photochromic Nitroprusside Anion (BEDT-TTF)4M[FeNO(CN)5]2, where M = Na+, K+, NH+4, Tl+, Rb+, and Cs+

The crystal and molecular structures of a family of three-component radical cation salts bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), (BEDT-TTF)₄M[NP]₂, where M = Na⁺, K⁺, NH⁺ ₄, Tl⁺, Rb⁺, and Cs⁺and NP is the nitroprusside anion [FeNO(CN)₅]^2–, are studied by X-ray structure analysis. These salts are isostructural and behave as stable metals down to helium temperatures. Their structures are characterized by radical cation layers of the "-type alternating with layers of complex anions [M⁺(NP^2–)₂]^3–. The conducting radical cation system and photochromic nitroprusside anion in the crystals were shown to affect each other. On the one hand, this changes the geometric parameters of the nitroprusside anion as compared to those of the Na₂[NP] · 2H₂O crystals in the ground state and, on the other hand, makes the geometries of the two crystallographically independent BEDT-TTF molecules with a different number of shortened contacts with the anion different. Based on the data of crystallochemical analysis of the (BEDT-TTF)₄M[FeNO(CN)₅]₂structures, we suggest their possible routes of chemical modification with the purpose of changing their physical properties.     

IR spectroscopic study of adsorption of ammmonia on Brønsted acid centers of a fluorinated surface of silica

The adsorption of aqueous ammonia solution vapor on a fluorinated surface of aerosil was studied by IR spectroscopy. The adsorption of NH₃ is accompanied by the appearance of absorption bands at 740, 1450, and 3330 cm^–1 in the IR spectra. The surface compounds were identified from the results of a study on the thermal degradation of adsorbed complexes and an analysis of literature data. The IR absorption bands at 1450 and 3330 cm^–1 correspond to deformational and stretching vibrations of the N-H bonds of the ammonium cation, The 740 cm^–1 band was assigned to the vibrations of the Si-F bonds in the complex anion, containing a fragment of SiO₂ surface, a fluorine atom, a hydroxyl group and a molecule of water. In this surface-coordinated compound, the silicon atom has a coordination number of six.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 747–751, November–December, 1986.     

An energy decomposition scheme applicable to strongly interacting systems

An energy decomposition scheme useful for the analysis of the coupled types of interactions in strongly interacting systems is developed within the Hartree-Fock approximation. A dominant characteristic of the scheme is that it involves the interactions between vacant orbitals of component molecules, as can be justified from the third-order perturbation theory. On the basis ofab initio molecular orbital calculations, the utility of the scheme is illustrated for the BH₃-NH₃ complexation and the S_N2 reaction of CH₄ with H^–. It is found that the charge transfer from electron donor (i.e. NH₃ or H^–) to acceptor (i.e. BH₃ or CH₄) is strongly coupled with the polarization of the acceptor, to contribute appreciably to the stabilization of the entire system. A specific role of this coupling mode in the progress of reactions is discussed.     

A novel three-dimensional mixed bridging–ligand complex with an unexpected 1,3-diaminopropane bridge

Reaction of K₃[Fe(CN)₆] with [Cu(tn)₂](ClO₄)₂ (tn=1,3-diaminopropane) leads to a novel mixed cyano and tn bridged three-dimensional (3D) bimetallic assembly (1), in which each [Fe(CN)₆]⁴⁻ anion connects six copper(II) cations via six CN⁻ groups, whereas each copper(II) cation is linked to three [Fe(CN)₆]⁴⁻ ions and two other copper(II) ions through Cu–NC–Fe and Cu–tn–Cu linkages, respectively. Magnetic studies reveal weak antiferromagnetic interactions between the nearest Cu^II (S=1/2) ions through the diamagnetic [Fe(CN)₆]⁴⁻ anion.     

IR and29Si NMR investigation of the influence of alkaline modification on the structure of hydrothermally dealuminated Y zeolites

The change in the structure of NH₄NaY zeolite (53 % NH₄ ⁺, Si/Al = 2.37) after hydrothermal treatment at 873 K followed by modification with aqueous KOH solution at 353 K was studied by IR and²⁹Si NMR spectroscopy. It has been shown that hydrolytic cleavage of the Al-O bond of the deammoniated zeolite sites by hydrothermal treatment predominates in the framework groups Si(OAl) _n (OSi)_4–n ,n=2, 3. Molecular water adsorbed on such a sample exists as hydrogen-bonded associates with hydrogen bonds of various strengths reaching that in ice-like structures (the band at 2468 cm^–1). Treatment with an alkali results in partial regeneration of the normal bridge bonds. The exchange of the protons of the terminal silanol groups with the alkaline cation prevents those groups from participating in the regeneration process.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 387–391, March, 1994.     

Transport of titanium(IV) ions across di-2-ethylhexylphosphoric acid-CCl4 supported liquid membranes

Transport study for Ti(IV) ions using di-2-ethylhexylphosphoric acid (D2EHPA) (carrier)-CCl₄ (diluent) liquid supported membrane in microporous polypropylene hydrophobic film has been performed. The parameters studied are effects of carrier, H₂SO₄, stripping agent (NH₄F) concentrations and temperature variation on flux and permeability coefficients of the metal ion. The optimum concentrations of transport found are 2.04 mol·dm^–3 D2EHPA, 1.0 mol·dm^–3 H₂SO₄ in the feed and 1 mol·dm^–3 NH₄F as stripping agent. The maximum flux and permeability coefficient determined are 1.32·10^–5 mol·m^–2·s^–1 and 8.02·10^–12 mol·m^–2·s^–1, respectively. The transport of this metal ion is increased with increase in temperature. The mechanism of transport appears to be based on coupled counter ion transport phenomenon.     

Effects of SO 4 2− , S2O 3 2− and HSO 4 − ion additives on the pitting corrosion of pure aluminium in 1 M NaCl solution at 40–70 °C

Effects of sulphate (SO₄^2–), thiosulphate (S₂O₃^2–) and hydrogensulphate (HSO₄^–) ion additives on the pitting corrosion of pure aluminium in 1 M NaCl solution have been investigated at various solution temperatures T_s, 40–70 °C using potentiodynamic polarisation experiment, double current step experiment and scanning electron microscopy (SEM). From the analysis of the galvanostatic potential transients obtained from the double current step experiment, it was suggested that both SO₄^2– and S₂O₃^2– ions retard the initiation of the etch pits, and that they also inhibit the passivation of the etch pits during the current interruption to promote the subsequent re-activation of the etch pits over the whole range of T_s. In contrast, it was found that HSO₄^– ions promote the initiation of the etch pits and at the same time, they enhance the passivation of the etch pits during the current interruption with rising T_s. From the SEM micrographs, it was revealed that as T_s increased the pit morphology changed from circular shape to irregular shape with rough surface in the presence of SO₄^2– or S₂O₃^2– ions, but it changed to strip-like shape in the presence of HSO₄^– ions. The beneficial effects of anion additives on the increase in surface area were discussed on the basis of the morphological change of the etch pits in the presence of anion additives.     

Characterization on Lead-Free Hybrid Perovskite [NH3(CH2)5NH3]CuCl4: Thermodynamic Properties and Molecular Dynamics

It is essential to develop novel zero- and two-dimensional hybrid perovskites to facilitate the development of eco-friendly solar cells. In this study, we investigated the structure and dynamics of [NH₃(CH₂)₅NH₃]CuCl₄ via various characterization techniques. Nuclear magnetic resonance (NMR) results indicated that the crystallographic environments of ¹H in NH₃ and ¹³C on C3, located close to NH₃ at both ends of the cation, were changed, indicating a large structural change of CuCl₆ connected to N–H···Cl. The thermal properties and structural dynamics of the [NH₃(CH₂)_nNH₃] cation in [NH₃(CH₂)_nNH₃]CuCl₄ (n = 2, 3, 4, and 5) crystals were compared using thermogravimetric analysis (TGA) and NMR results for the methylene chain. The ¹H and ¹³C spin-lattice relaxation times (T_1ρ) exhibited similar trends upon the variation of the methylene chain length, with n = 2 exhibiting shorter T_1ρ values than n = 3, 4, and 5. The difference in T_1ρ values was related to the length of the cation, and the shorter chain length (n = 2) exhibited a shorter T_1ρ owing to the one closest to the paramagnetic Cu²⁺ ions.     

Al3Li4(BH4)13: A Complex Double‐Cation Borohydride with a New Structure

The new double‐cation Al–Li–borohydride is an attractive candidate material for hydrogen storage due to a very low hydrogen desorption temperature (～70 °C) combined with a high hydrogen density (17.2 wt %). It was synthesised by high‐energy ball milling of AlCl₃ and LiBH₄. The structure of the compound was determined from image‐plate synchrotron powder diffraction supported by DFT calculations. The material shows a unique 3D framework structure within the borohydrides (space group=P‐43n, a=11.3640(3) Å). The unexpected composition Al₃Li₄(BH₄)₁₃ can be rationalized on the basis of a complex cation [(BH₄)Li₄]³⁺ and a complex anion [Al(BH₄)₄]^?. The refinements from synchrotron powder diffraction of different samples revealed the presence of limited amounts of chloride ions replacing the borohydride on one site. In situ Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal desorption measurements were used to study the decomposition pathway of the compound. Al–Li–borohydride decomposes at ～70 °C, forming LiBH₄. The high mass loss of about 20 % during the decomposition indicates the release of not only hydrogen but also diborane.     

Non-convertional hydrogen bonding interaction of BH3NH3 complexes: a comparative theoretical study

A new type of hydrogen bond, called a dihydrogen bond, has recently been introduced. In this bond hydrogen is donated to (hydridic) hydrogen. In this paper, ab initio HF, MP2 and DFT(B3LYP) levels of theory with different basis sets in combination with counterpoise procedure for basis set superposition error correction have been applied to BH₃NH₃ dimer and BH₃NH₃ complexes of methane, hydrogen cyanide, ammonia, water, methanol and hydrogen fluoride to understand the features of dihydrogen bond. The optimized geometric parameters and interaction energies for various isomers at different levels are estimated. The structures obtained at different computational levels are in agreement with each other. Dihydrogen bond does not occur in both BH₃NH₃⋯CH₄ and BH₃NH₃⋯NH₃ complexes. Apart from the B–H⋯H–N dihydrogen bond found in the BH₃NH₃ crystal and dimmer, the B–H⋯H–X (XC, O, F) dihydrogen bonds have been observed in the BH₃NH₃⋯HCN, BH₃NH₃⋯H₂O, BH₃NH₃⋯CH₃OH and BH₃NH₃⋯HF complexes, while the classic H bonds also exist in the last three complexes. As for the complexes in which only dihydrogen bonds appear the strength of dihydrogen bonds ranges from 17.9 to 18.9 kJ mol⁻¹ at B3LYP/6-311++g(d,p) level. Binding energies obtained from the MP2 and B3LYP optimized structures are more sensitive to basis sets than those from the HF method. Larger basis functions generally tend to produce slightly longer intermolecular distances, and the B3LYP and MP2 methods generate shorter intermolecular distances though they usually produce longer bond lengths compared with those at the HF level. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. Finally the solution phase studies on BH₃NH₃⋯HF complex are also carried out using the Onsager reaction field model with a range of dielectric constants from 2 to 80 at B3LYP/6-311++g(d,p) level.     

Binding of permanganate anion to pentaammineazidocobalt(III) cation in solution and solid phases: synthesis,characterization, X-ray structure,and genotoxic effects of [Co(NH3)5N3](MnO4)2⋅H2O

A pentaammineazidocobalt(III) complex, [Co(NH₃)₅N₃](MnO₄)₂XH₂O has been synthesized by an one-pot synthesis method. It was characterized by studies such as infrared (IR) and UV-visible spectroscopy. The single crystal X-ray structure analysis revealed that the title complex crystallizes in space group Cc. The cobalt center is six coordinated with slightly octahedral geometry. The supramolecular architecture is also formed by intermolecular N-H…O (anion and H₂O) and Mn-O…O-H hydrogen bonds. The binding property of the cation, [Co(NH₃)₅N₃]²⁺ with the anion, MnO₄^– has also been determined (in solution phase) with the help of UV-visible spectroscopic titrations. Further, the genotoxic effects of KMnO₄, [Co(NH₃)₅N₃]Cl₂ and [Co(NH₃)₅N₃](MnO₄)₂XH₂O were studied using Allium cepa root chromosomal aberration assay and it revealed that the genotoxicity of the newly synthesized complex is 1.97–1.76 fold, which is less compared to KMnO₄. The order of genotoxic potential has been observed to be KMnO₄ > [Co(NH₃)₅N₃](MnO₄)₂XH₂O > [Co(NH₃)₅N₃]Cl₂.     

Reaction of tetrabutylammonium octahydrotriborate with triphenylphosphine

Conclusions The B₃H₈ ^– anion dissociates upon the reaction of Bu₄NB₃H₈ with PPh₃ in benzene above 70°C with the formation of the BH₄ ^– ion and B₂H₄, which is separated as the B₂H₄2PPh₃ adduct. This reaction was found to be reversible.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2120–2122, September, 1987.     

Adsorption properties of charcoal impregnated with stannic chloride

Adsorption behaviour of the individual tracer ions:¹³⁴Cs(I),^85,89Sr(II),^131,133Ba (II),⁹⁰Y(III),¹⁴¹Ce(III),^152,154Eu(III),⁹⁵Zr(IV),^175,181Hf(IV),⁹⁵Nb(V),⁶⁰Co(II),¹¹⁵Cd(II),^99mTc(VII), and¹³¹I(-I) on charcoal impregnated with stannic chloride from Hcl solutions, was investigated. Batch equilibrium distribution coefficients of the respective ions indicated strong anion exchange properties towards impregnated charcoal. The column breakthrough sorption capacity was of the order of 0.62–0.66 meq·g^–1 of dry adsorbent. Small chromatographic columns of impregnated charcoal could achieve rapid and quantitative separation procedures in HCl medium. Strongly adsorbed anions such as TcO ₄ ^– and I^– ions could be eluted with NH₄SCN and NH₄NO₂ eluents, respectively.