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The Suzuki–Miyaura reaction of 4-amino-3,5-dibromo-2,6-lutidine with various ortho-substituted phenylboronic acids resulted in the formation of a series of mono- and diarylated lutidines in the form of atropisomers. The absolute stereochemistry of the chiral compounds was established, in some cases, by X-ray crystal structure analysis and HPLC-ECD (ECD = electronic circular dichroism) in combination with time-dependent density functional theory (TDDFT) calculations.

The present study was designed to check enzyme (esterase and α-glucosidase) inhibition potential of newly synthesized thiazolidinones. Two precursors from ethylene diamine were prepared and further condensed with different aromatic aldehydes yielded fourteen different compounds. The synthesized compound ‘a’ was characterized with single crystal X-Ray diffraction (SC-XRD) technique, while the structures of all others were determined with FTIR and NMR (1H and 13C) spectroscopy. The compounds were further theoretically optimized through Gaussian 9 software and calculated their different parameters and energy gap between HOMO and LUMO. In-vitro enzyme inhibition studies were carried out spectrophotometrically which depicted that these molecules may be good therapeutic for targeted enzymes and their related diseases. Docking results of the synthetic thiazolidinone also advocated experimental out comes of the under studied compounds.

A combined experimental–theoretical study of silver(I) and silver(II) fluorides under high pressure is reported. For AgI, the CsCl-type structure is stable to at least 39 GPa; the overtone of the IR-active mode is seen in the Raman spectrum. Its AgIIF2 sibling is a unique compound in many ways: it is more covalent than other known difluorides, crystallizes in a layered structure, and is enormously reactive. Using X-ray diffraction and guided by theoretical calculations (density functional theory), we have been able to elucidate crystal structures of high-pressure polymorphs of AgF2. The transition from ambient pressure to an unprecedented nanotubular structure takes place via an intermediate orthorhombic layered structure, which lacks an inversion center. The observed phase transitions are discussed within the broader framework of the fluorite → cotunnite → Ni2In series, which has been seen for other metal difluorides.

Here we redetermine the crystal structure of Ag(II)SO4, an unusual d9 system, at 1 atm from powder X-ray data and we report hydrostatic pressure X-ray diffraction experiments on Ag(II)SO4 inside the diamond anvil cell. AgSO4 crystallizes in the monoclinic C2/c cell, with a = 12.8476(2) A, b = 13.6690(4) A, c = 9.36678(19) A, β = 47.5653(13)°, and V = 1214.04(5) A3 (Z = 16). AgSO4 exhibits bulk modulus, B0, of 36.9 GPa, and undergoes sluggish decomposition at ∼23 GPa yielding a high-pressure phase of Ag2S2O7 (K2S2O7-type), with the substrate and product coexisting at 30 GPa. Theoretical calculations within Density Functional Theory for the C2/c cell nicely reproduce the observed trend for lattice constants as well as the B0 values of AgSO4, and suggest that the rigidity of the infinite [Ag(SO4)] chains as well as the Jahn–Teller effect for the Ag(II) cation persist even at 30 GPa.

Anhydrous fluorosulfates of sodium(I) and thallium(I) have been structurally characterized for the first time; structure of a novel polymorphic form of rubidium(I) fluorosulfate is also reported. NaSO3F is hexagonal (P63/mmc, a = b = 5.4812(2) A, c = 6.5172(3) A, Z = 2), while RbSO3F and TlSO3F are orthorhombic an both adopt the Pnma space group, but despite similar ionic radii of metal cations they are not isostructural with each other (Rb: a = 8.7812(7) A, b = 6.0318(6) A, c = 7.5108(6) A, Z = 4; Tl: a = 5.2205(3) A, b = 5.5141(2) A, c = 13.4378(7) A, Z = 4). The three fluorosulfates studied here complete the list of fluorosulfates of monovalent metals, for which the crystal structures have been determined.

Trifluoromethansulfonate of silver(I), AgSO(3)CF(3) (abbreviated AgOTf), extensively used in organic chemistry, and its fluorosulfate homologue, AgSO(3)F, have been structurally characterized for the first time. The crystal structures of both homologues differ substantially from each other. AgOTf crystallizes in a hexagonal system (R3 space group, No.148) with a = b = 5.312(3) Å and c = 32.66(2) Å, while AgSO(3)F crystallizes in a monoclinic system in the centrosymmetric P2(1)/m space group (No.11) with a = 5.4128(10) Å, b = 8.1739(14) Å, c = 7.5436(17) Å, and β = 94.599(18)°, adopting a unique structure type (100 K data). There are two types of fluorosulfate anions in the structure; in one type the F atom is engaged in chemical bonding to Ag(I) and in the other type the F atom is terminal; accordingly, two resonances are seen in the (19)F NMR spectrum of AgSO(3)F. Theoretical analysis of the electronic band structure and electronic density of states, as well as assignment of the mid- and far-infrared absorption and Raman scattering spectra for both compounds, have been performed based on the periodic DFT calculations. AgSO(3)F exhibits an unusually low melting temperature of 156 °C and anomalously low value of melting heat (ca. 1 kJ mol(-1)), which we associate with (i) disorder of its anionic sublattice and (ii) the presence of 2D sheets in the crystal structure, which are weakly bonded with each other via long Ag-O(F) contacts. AgSO(3)F decomposes thermally above 250 °C, yielding mostly Ag(2)SO(4) and liberating SO(2)F(2). AgOTf is much more thermally stable than AgSO(3)F; it undergoes two consecutive crystallographic phase transitions at 284 °C and 326 °C followed by melting at 383 °C; its thermal decomposition commences above 400 °C leading at 500 °C to crystalline Ag(2)SO(4) and an unidentified phase as major products of decomposition in the solid state.

We report the crystal structure and magnetic properties of a novel β polymorph of K 2 AgF 4 . β-K 2 AgF 4 is paramagnetic above 20 K and exhibits a low Curie temperature (0 < 5 K). Solid state DFT (GGA and GGA+U) calculations were performed to analyze the electronic and magnetic structure of β-K 2 AgF 4 at 0 K/0 GPa, reproducing correctly the ferromagnetic (FM) semiconductor ground state with the band gap at the Fermi level of approximately 1.65 eV. Furthermore, we show that the novel β form is thermodynamically favoured over the previously reported two-dimensional α form and can be formed either by slow spontaneous exothermic α to β phase transition occurring on heating or direct synthesis from KF and AgF 2 at 300 °C. The relative stability of the α and β phases is rationalized in terms of the size of the M + cation in the M 2 M'F 4 series (M = Na, K, Cs, M' = Cu, Ag) and the mismatch between [MF] and [M'F 4/2 ] sublattices in the layered perovskite α form.

1,2-Diaminoethane has been in-situ pressure- and temperature-frozen; apart from two known low-temperature phases, Iα and II, three new phases, Iβ, Iγ and III, have been observed and their structures determined by X-ray diffraction. The measurements at 0.1 MPa were carried out at 274, 243 and 224 K, and 296 K measurements were made at 0.15 GPa (phase Iα), at 0.3 and 1.1 GPa (phase Iβ), at 1.5 GPa (phase Iγ), and at 0.2, 0.3 and 0.5 GPa (phase III). All these phases are monoclinic, space group P21/c, but the unit-cell dimension of phases Iα and III are very different at 296 K: a Iα = 5.078 (5), b Iα = 7.204 (8), c Iα = 5.528 (20) Å, β Iα = 115.2 (2)° at 0.15 GPa, and a III = 5.10 (3), b III = 5.212 (2), c III = 7.262 (12) Å, β III = 111.6 (4)° at 0.2 GPa, respectively; in both phases Z = 2. An ambient-pressure low-temperature phase II has been observed below 189 K. Discontinuities in the unit-cell dimensions and in the N...N distance mark the isostructural transition between phases Iα and Iβ at 0.2 GPa, which can be attributed to a damping process of the NH2 group rotations. In phase Iγ the unit-cell parameter a doubles and Z increases to 4. The molecule has inversion symmetry in all the structures determined. 1,2-Diaminoethane can be considered as a simple structural ice analogue, but with NH...N hydrogen bonds and with the H-atom donors (four in one molecule) in excess over H-atom acceptors (two per molecule). Thus, the transformations of 1,2-diaminoethane phases involving the conformational dynamics affect the hydrogen-bonding geometry and molecular association in the crystal. The 1,2-diaminoethane:1,2-dihydroxyethane mixture has been separated by pressure-freezing, and a solid 1,2-diaminoethane crystal in liquid 1,2-dihyroxyethane has been obtained.

The crystal structure of benzene, C6H6, in situ pressure-frozen in phase I, has been determined by X-ray diffraction at 0.30, 0.70 and 1.10 GPa, and 296 K. The molecular aggregation within phase I is consistent with van der Waals contacts and electrostatic attraction of the positive net atomic charges at the H atoms with the negative net charges of the C atoms. The C—H...aromatic ring centre contacts are the most prominent feature of the two experimentaly determined benzene crystal structures in phases I and III, whereas no stacking of the molecules has been observed. This specific crystal packing is a likely reason for the exceptionally high polymerization pressure of benzene. The changes of molecular arrangement within phase I on elevating the pressure and lowering the temperature are analogous.

Conformational disorder and inversions of the lactone ring induce structural transformations in the crystals of 6-hydroxy-4,4,5,7,8-pentamethyl-3,4-dihydrocoumarin, C14H18O3. The onset of ordering of the lactone ring at 300 K proceeds continuously, changes the space group from P21/m to P21/c and doubles the unit cell; the abrupt inversion of the lactone rings at 225 K changes the crystal translational symmetry in the (010) plane. The mechanism combining the molecular conformation and dynamics with the crystal structure, its symmetry, and phase transitions is presented.

High purity samples of a [Ag(pyrazine)(2)]S(2)O(8) complex were obtained using modified synthetic pathways. Di(pyrazine)silver(II) peroxydisulfate is sensitive to moisture forming [Ag(pyrazine)(2)](S(2)O(8))(H(2)O) hydrate which degrades over time yielding HSO(4)(-) derivatives and releasing oxygen. One polymorphic form of pyrazinium hydrogensulfate, β-(pyrazineH(+))(HSO(4)(-)), is found among the products of chemical decomposition together with unique [Ag(i)(pyrazine)](5)(H(2)O)(2)(HSO(4))(2)[H(SO(4))(2)]. Chemical degradation of [Ag(pyrazine)(2)]S(2)O(8) in the presence of trace amounts of moisture can explain the very low yield of wet synthesis (11-15%). Attempts have failed to obtain a mixed valence Ag(II)/Ag(I) pyrazine complex via partial chemical reduction of the [Ag(pyrazine)(2)]S(2)O(8) precursor with a variety of inorganic and organic reducing agents, or via controlled thermal decomposition. Thermal degradation of [Ag(pyrazine)(2)]S(2)O(8) containing occluded water proceeds at T90 °C via evolution of O(2); simultaneous release of pyrazine and SO(3) is observed during the next stages of thermal decomposition (120-285 °C), while Ag(2)SO(4) and Ag are obtained upon heating to 400-450 °C.

We describe the successful synthesis of the first mixed-cation (pseudoternary) amidoborane, Na[Li(NH(2)BH(3))(2)], with theoretical hydrogen capacity of 11.1 wt%. Na[Li(NH(2)BH(3))(2)] crystallizes triclinic (P1) with a = 5.0197(4) Å, b = 7.1203(7) Å, c = 8.9198(9) Å, α = 103.003(6)°, β = 102.200(5)°, γ = 103.575(5)°, and V = 289.98(5) Å(3) (Z = 2), as additionally confirmed by Density Functional Theory calculations. Its crystal structure is topologically different from those of its orthorhombic LiNH(2)BH(3) and NaNH(2)BH(3) constituents, with distinctly different coordination spheres of Li (3 N atoms and 1 hydride anion) and Na (6 hydride anions). Na[Li(NH(2)BH(3))(2)], which may be viewed as a product of a Lewis acid (LiNH(2)BH(3))/Lewis base (NaNH(2)BH(3)) reaction, is an important candidate for a novel lightweight hydrogen storage material. The title material decomposes at low temperature (with onset at 75 °C, 6.0% mass loss up to 110 °C, and an additional 3.0% up to 200 °C) while evolving hydrogen contaminated with ammonia.