Search

Most known compounds with five-coordinated Ti4+ are natural and synthetic titanosilicates. The crystal structure of natural fresnoite, Ba2TiSi2O8 [tetragonal, space group P4bm, a = 8.510 (1) Å, c = 5.197 (1) Å, V = 376.4 (1) Å3, Z = 2], has been refined to R = 0.011 on the basis of 807 unique single-crystal reflections with I > 2σ(I). Titanium has fivefold coordination with one short (`titanyl') bond of 1.692 (5) Å. Bonds in the TiO5 polyhedron are discussed in comparison to analogous coordination polyhedra in other minerals and compounds. A review of all known compounds with Ti4+O5 polyhedra shows that most of them are titanosilicates in which titanium forms a short Ti—O bond (∼1.61 to ∼1.77 Å). Poor Gladstone–Dale compatibility between chemical composition, optical characteristics and density of these compounds is explained by the anomalous contribution of [5]Ti4+ to the optical properties as shown by calculations based on the relationship between electronic polarizabilities and refractive indices. An improved Gladstone–Dale coefficient of 0.29 is suggested for TiO2 with [5]Ti4+. A negative correlation between `titanyl' bond lengths and wavenumbers of the bands of Ti—O stretching vibrations (in the range of 890–830 cm−1) in infrared and Raman spectra is observed.

Betzite, ideally Na6Ca2(Al6Si6O24)Cl4, a new cancrinite-group mineral, was discovered in a metasomatically altered (pyrometamorphosed) calcic xenolith, hosted by alkaline basalt at the Bellerberg paleovolcano in the Eastern Eifel region, Rhineland-Palatinate, Germany. The associated minerals are anorthite, phlogopite, diopside, grossular, fluorite, calcite, a tobermorite-like mineral, and vanadoallanite-(Ce). Betzite occurs as colorless hexagonal prismatic crystals up to 2 mm long and up to 0.5 mm thick. The new mineral is brittle, with a Mohs' hardness of 5½. Distinct cleavage on {100} and parting on {0001} are observed. The Dmeas = 2.38(2) g/cm3 and Dcalc = 2.363 g/cm3. Betzite is optically uniaxial (+) with ω = 1.528(2) and ε = 1.545(3). The IR spectrum is given. The chemical composition of betzite is (wt.%; electron microprobe, H2O determined by the modified Penfield method): Na2O 11.88, K2O 4.82, CaO 10.74, MgO 0.21, Al2O3 27.32, Fe2O3 0.68, SiO2 32.84, SO3 1.89, Cl 10.48, H2O 1.10, −O≡Cl −2.37, total 99.59. The empirical formula is Na4.22K1.13Ca2.11Mg0.06(Si6.01Al5.90Fe3+0.09O24)Cl3.25(SO4)0.26(H1.34O0.64). The crystal structure was determined using single-crystal X-ray diffraction data. It is hexagonal, space group P63, a = 12.8166(9) Å, c = 5.3562(3) Å, V = 761.95(12) Å3 (at a temperature of 100 K) and Z = 3. Betzite is a dimorph of quadridavyne, with a disordered distribution of extra-framework components occupying channels. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 11.14 (31) (100), 4.833 (93) (101), 3.715 (95) (300), 3.313 (100) (211), 2.787 (37) (400), 2.681 (56) (002, 131), 2.474 (35) (112, 401), 2.146 (24) (330). The mineral is named in honor of the German amateur mineralogist Volker Betz (b. 1947).

The new eudialyte-group mineral selsurtite, ideally (H3O)12Na3(Ca3Mn3)(Na2Fe)Zr3□Si[Si24O69(OH)3](OH)Cl⋅H2O, was discovered in metasomatic peralkaline rock from the Flora mountain, northern spur of the Selsurt mountain, Lovozero alkaline massif, Kola Peninsula, Russia. The associated minerals are aegirine, albite and orthoclase, as well as accessory lorenzenite, calciomurmanite, natrolite, lamprophyllite and sergevanite. Selsurtite occurs as brownish-red to reddish-orange, equant or flattened on (0001) crystals up to 2 mm across and elongate crystals up to 3 cm long. The main crystal forms are {0001}, {11$\bar{2}$0}, and {10$\bar{1}$1}. Selsurtite is brittle, with the Mohs’ hardness of 5. No cleavage is observed. Parting is distinct on (001). D(meas) = 2.73(2) and D(calc) = 2.722 g⋅cm–3. Selsurtite is optically uniaxial (–), with ω = 1.598(2) and ɛ = 1.595(2). The chemical composition is (wt.%, electron microprobe): Na2O 6.48, K2O 0.27, MgO 0.10, CaO 6.83, MnO 4.73, FeO 1.18, SrO 1.88, La2O3 0.57, Ce2O3 1.07, Pr2O3 0.20, Nd2O3 0.44, Al2O3 0.29, SiO2 50.81, ZrO2 13.50, HfO2 0.45, TiO2 0.61, Nb2О5 1.10, Cl 1.01, SO3 0.29, H2O 8.10, –O≡Cl –0.23, total 99.68. The empirical formula is H25.94Na6.03K0.16Mg0.07Ca3.51Sr0.52Ce0.19La0.10Nd0.08Pr0.03Mn1.91Fe0.47Ti0.22Zr3.16Hf0.06Nb0.24Si24.40Al0.16S0.10Cl0.82O79.13. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.0484. Selsurtite is trigonal, space group R3, with a = 14.1475(7) Å, c = 30.3609(12) Å, V = 5262.65(7) Å3 and Z = 3. Infrared and Raman spectra show that hydronium cations are involved in very strong hydrogen bonds and form Zundel- and Eigen-like complexes. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 11.38 (56)(101), 7.08 (59)(110), 5.69 (36)(202), 4.318 (72)(205), 3.793 (36)(303), 3.544 (72)(027, 220, 009), 2.970 (100)(315) and 2.844 (100)(404). The mineral is named after the discovery locality.

The crystal structure of a potentially new mineral, the Fe2+-dominant analogue of armalcolite with the idealized formula Fe2+Ti2O5 has been solved. The sample studied originates from a pneumatolytic association related to the lamproite complex of SE Spain. The mineral is orthorhombic, space group Cmcm, the unit-cell parameters are a = 3.7325(1) A, b = 9.7649(4) A, c = 9.9902(3) A, V = 364.12(2) A3. The crystal-chemical formula $${{^{M}}^{1}}{{({\text{M}}{{{\text{g}}}_{{0.19}}}{\text{Fe}}_{{0.25}}^{{2 + }}{\text{Fe}}_{{0.26}}^{{3 + }}{\text{T}}{{{\text{i}}}_{{0.30}}})}^{{2.86 + }}}$$ $${{{{[}^{M}}^{2}{{({\text{T}}{{{\text{i}}}_{{0.65}}}{\text{Fe}}_{{0.27}}^{{3 + }}{\text{Fe}}_{{0.08}}^{{2 + }})}^{{3.57 + }}}]}_{2}}{{{\text{O}}}_{5}}$$ (Z = 4) is in good agreement with the chemical composition of the mineral.

The crystal structures of ion-exchange products of the zeolite-group mineral amicite from Khibiny Alkaline Massif with silver and rubidium salts have been studied. The investigated samples are monoclinic (sp. gr. P21 and I2/a); their crystallochemical formulas (Z = 1) are Ag8(Al8Si8O32) ⋅ 10.6H2O and K0.4Na0.7Rb6.9(Al8Si8O32) ⋅ 4.5H2O; the unit cell parameters are a = 9.272(2) and 10.043(2) A, b = 9.997(2) and 9.748(2) A, c = 10.380(3) and 10.265(2) A, β = 90.821(8)° and 90.09(3)°, V = 962.0(4) and 1005.0(3) A3, respectively. In the Ag-amicite structure, 22 partially occupied sites of the extra-framework components (Ag and H2O) are localized. In the Rb-amicite structure, most of rubidium atoms are located in two sites with the occupancies of 0.414(6) and 0.389(5). The cross-sectional areas of the zeolite channels are 3.5 × 4.5 and 2.3 × 6.3 A2 for Ag-amicite and 3.0 × 4.3 and 3.0 × 3.9 A2 for Rb-amicite.

Processes and products of ion exchange of gunterblassite (K,Ca,Ba,Na)3–xFe1–y[(Si,Al)13O25(OH,O)4]·7H2O (microporous silicate, structurally intermediate between smectites and zeolites) and three samples of zeolite gmelinite (Na,K,Ca,Mg)x[(Si,Al)12O24)·nH2O of different composition with cations of various metals were studied. It was shown that gunterblassite exhibits high activity and sorption capacity with respect to Rb+, Cs+, Ag+ cations and, to a lesser extent, Pb2+ and Ba2+: even at room temperature for 1 h, the concentration of M2O (M = Rb, Cs, Ag) in the sorbent reaches 10–13 wt %. The ion exchange in gmelinite occurs according to the frontal mechanism, propagating from the periphery of the crystal to its center. In reactions with Pb2+, the activity of gmelinite increases with a rise in its sodium content and decreases with a rise in potassium content. The crystal structure of Pb-substituted gmelinite was studied and it was shown that Pb2+ ions populate both zeolite channels. Synthetic gmelinite obtained from cheap natural raw materials and fly ash from thermal power plants can be used to purify water from lead.

The structure of the radical anion salt (RAS) of 7,7,8,8-tetracyanedimethane (TCNQ) with a cation based on 2-amin-5-chloro-pyridine (2-NH2-5-Cl–Py, Am), that is, (N–CH3-2-NH2-5-Cl–Py) (TCNQ) (CH3CN), (I) is presented. Unlike most TCNQ RASs, which contain flat TCNQ particle stacks, RAS I contains practically isolated (TCNQ)$$_{2}^{{2 - }}$$ π-dimers with unusually short distances between the planes in the dimers: 3.24 A. In the RAS I IR spectra special features are observed that correspond to the vibronic interactions of molecular vibrations.

The C-methylthio derivatives of cobalt bis(dicarbollide) were synthesized by reaction of anhydrous CoCl2 with nido-carborane [7-MeS-7,8-C2B9H11]− and isolated as a mixture of rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− and meso-[1,2′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− isomers. The structures of both isomers were studied using DFT quantum chemical calculations. The most preferable geometry of rotamers and the stabilization energy of C-methylthio derivatives of cobalt bis(dicarbolide) were calculated. The (BEDT-TTF)[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2] salt was prepared and its structure was determined by single crystal X-ray diffraction. The cisoid conformation of the rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− anion is stabilized by short intramolecular CH⋯S hydrogen and BH⋯S chalcogen bonds between the dicarbollide ligands, that is in good agreement with the data of quantum chemical calculations.

The radical-cationic salts based on tetrathiafulvalene derivatives and bis(dicarbollide) transition metal complexes [3,3′-M(1,2-C2B9H11)2]− (M = Co, Ni, Fe, Cr) are promising for the creation of new molecular conductive materials due to the almost unlimited possibilities of their modification. The relationships between the properties of both components of the cation-radical salts, their crystal structure, and electrical and magnetic properties have been analyzed on the basis of the literature and our own data. The effect of various substituents in metallacarborane anions on the structure and physical properties of their radical cation salts based on tetrathiafulvalene and its derivatives has been revealed. Data on the structure and properties of the radical cation salts with other borate anions are presented for comparison.

Anion-radical salt of 7,7,8,8-tetracyanoquinodimethane with N-methyl-2,2'-dipyridyl cation is synthesized. Its composition is determined using electron spectroscopy and elemental analysis. The crystal and molecular structures of the salt are determined using X-ray diffraction (XRD) analysis. The salt contains homogeneous stacks of 7,7,8,8-tetracyanoquinodimethane particles, which is a necessary condition for high electrical conductivity. The IR spectrum of the salt exhibits specific features characteristic of organic metals: continuous absorption (electron continuum) and manifestation of electron–phonon interaction. These characteristics of the salt give grounds to assign it to organic metals.

The new crichtonite-group mineral saranovskite, ideally SrCaFe2+2(Cr4Ti2)Ti12O38, was discovered in the Glavnoe Saranovskoe deposit, Middle Urals, Russia, and named after the type locality. The associated minerals are chromite, Cr-bearing clinochlore, and calcite. Saranovskite forms black crude equant crystals about 2 mm across. The lustre is submetallic, and the streak is brownish-gray. Cleavage is not observed. The Mohs hardness is 6. Density calculated using the empirical formula is equal to 4.501 g cm–3. The reflectance spectra in visible range are given. The IR spectrum shows the absence of H-, B- and C-bearing groups. The Raman spectrum of saranovskite confirms the absence of H-bearing groups and indicates a rather high degree of ordering of Ti4+ and lower-valence cations. The chemical composition of saranovskite is (wt.%; electron microprobe, total iron apportioned between FeO and Fe2O3 taking into account charge balance): MgO 2.01, CaO 1.43, MnO 0.21, FeO 8.14, SrO 3.27, BaO 2.18, Al2O3 0.53, Sc2O3 0.69, Cr2O3 10.27, Fe2O3 2.19, Y2O3 1.56, La2O3 0.94, Ce2O3 0.91, Pr2O3 0.14, Nd2O3 0.35, TiO2 64.25, ZrO2 0.58, total 99.65. The crystal chemical formula of saranovskite is (Sr0.55Ba0.25Ln0.10Ca0.10)(Ca0.36Y0.25Ln0.16Fe2+0.08Zr0.10Mn0.05) (Fe2+1.12Mg0.88)(Cr3+2.34Ti2.28Fe2+0.91Fe3+0.11Al0.18Sc3+0.18)(Ti5.82Fe3+0.18)Ti6.0O38. The idealized formula is SrCaFe2+2(Cr4Ti2)Ti12O38. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.0243. The new mineral is isostructural to other crichtonite-group members. Saranovskite is trigonal, space group R $$\overline{3}$$ , with a = 10.3553(2) A, c = 20.7301(4) A, V = 1925.12(8) A3 and Z = 3. The strongest lines of the powder X-ray diffraction pattern [d, A (I, %) (hkl)] are: 3.398 (75) (024), 2.881 (100) (– 126), 2.842 (65) (– 234), 2.247 (67) (– 144). 2.137 (76) (– 345), 1.799 (63) (– 348), 1.597 (72) (– 1.4.10, 152), 1.439 (76) (520).

The first molecular conductors based on bis(1,3-propylenedithio)tetrathiafulvalene and transition metal bis(dicarbollides) (BPDT-TTF)[3,3′-Сr(1,2-C2B9H11)2] (1) and (BPDT-TTF)[3,3′-Сo(1,2-C2B9H11)2] (2) were synthesized and their crystal structures were determined by X-ray analysis. The electric conductivity measurements revealed that these compounds are semiconductors at room temperature.

The synthesis of a radical-cation salt based on a derivative of tetrathiafulvalene, (ET)2[3,3′-Cr(1,2-C2B9H11)2] (ET = bis(ethylenedithio)tetrathiafulvalenium), was accomplished by electrochemical anodic oxidation of ET in the presence of (Me4N)[3,3´-Cr(1,2-C2B9H11)2] in the galvanostatic regime. An electric conductivity σ (293 K) = 7 × 10−3 Ohm−1 cm−1 with semiconductor activation energy Ea ≅ 0.1 eV in the range of 127–300 K was observed. The crystal structure of (ET)2[3,3′-Cr(1,2-C2B9H11)2] was determined by X-ray diffraction at 173 K, revealing the presence of structural tetramers in radical-cation stacks. The magnetic properties of the complex were investigated in the temperature range 1.8–300 K using magnetometry and EPR, showing that the magnetic structure of (ET)2[3,3′-Cr(1,2-C2B9H11)2] consists of two independent magnetic subsystems. Cation radicals form a rectangular magnetic lattice in the ab-plane with significant antiferromagnetic exchange interactions. The chromium bis(dicarbollide) anions are characterized by unusually strong positive zero-field splitting of the Cr(III) ions, which was confirmed by ab initio calculations.

New radical-cation salts based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) were synthesized: (ЕТ)2[8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2] (1) and (ЕТ)[8,8′-I2-3,3′-Fe(1,2-C2B9H10)2] (2). Their crystal structures were studied by X-ray analysis, electroconducting and magnetic properties were measured in a wide temperature range. Salts (1) and (2) appeared to be the first radical-cation salts with [8,8′-I2-3,3′-Fe(1,2-C2B9H10)2]- and [8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2]- anions, respectively. In the literature [8,8′-I2-3,3′-Fe(1,2-C2B9H10)2]- and [8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2]- anions are presented for the first time. Salts (1) and (2) were found to be paramagnetic. Their room temperature conductivities were 2 and 1·10−6 Ohm−1cm−1, respectively.

New radical-cation salts based on tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenefulvalene (TMsTSF) with metallacarborane anions (TMTTF)[3,3′-Cr(1,2-C2B9H11)2], (TMTTF)[3,3′-Fe(1,2-C2B9H11)2], and (TMTSF)2[3,3′-Cr(1,2-C2B9H11)2] were synthesized by electrocrystallization. Their crystal structures were determined by single crystal X-ray diffraction, and their electrophysical properties in a wide temperature range were studied. The first two salts are dielectrics, while the third one is a narrow-gap semiconductor: σRT = 5 × 10−3 Ohm−1cm−1; Ea ≈ 0.04 eV (aprox. 320 cm−1).

The new molecular conductors based on unconventional tetrathiafulvalene π-donors 4,5-ethylenedithio-4′,5′-(2-oxa-1,3-propylenedithio)tetrathiafulvalene (EOTT) and bis(1,3-propylenedithio)tetrathiafulvalene (BPDT-TTF) and metallacarborane anion [8,8′-Cl2–3,3′-Fe(1,2-C2B9H10)2]− were synthesized and their crystal structures were determined by single crystal X-ray diffraction. The electric conductivity study proved that both compounds (EOTT)2[8,8′-Cl2–3,3′-Fe(1,2-C2B9H10)2] and (BPDT-TTF)2[8,8′-Cl2–3,3′-Fe(1,2-C2B9H10)2] are semiconductors at room temperature.

The

Elpidite from the Lovozero alkaline complex, Kola Peninsula, Russia, and Ag-exchanged forms of elpidite from two different localities (Lovozero and Khan Bogdo, Mongolia) were studied by means of single-crystal X-ray diffraction, electron microprobe analysis, thermogravimetry and IR spectroscopy. All studied samples retain the heteropolyhedral framework consisting of double Si6O15 chains (ribbons) and isolated ZrO6 octahedra. Zeolitic cavities in the initial elpidite from Lovozero (space group Pbm2, a = 14.6127(7), b = 7.3383(4), c = 7.1148(3) &Aring, V = 762.94(6) &Aring, 3) are occupied by Na+ cations and H2O molecules. Both Ag-exchanged forms are characterized by evident distortions of the heteropolyhedral framework and a strongly disordered arrangement of extra-framework cations which results in the appearance of the 14-14-14 &Aring, unit cell (a = 14.1755(7), b = 14.6306(9), c = 14.2896(7) &Aring, V = 2963.6(3) &Aring, 3 for the Ag-exchanged form of elpidite from Lovozero and a = 14.1411(5), b = 14.5948(4), c = 14.3035(5) &Aring, V = 2952.04(17) &Aring, 3 for the Ag-exchanged form of elpidite from Khan Bogdo) and space group Cmce. Elpidite from both localities demonstrates a high exchange capacity to Ag. Exchanged Ag+ cations preferably occupy the sites that are close to the Na sites in the initial elpidite. The paper also contains a review of crystal chemical data on elpidite and its laboratory-modified forms.

The new radical cation salts based on transition metal bis(dicarbollides) with dibenzotetrathiafulvalene (DBTTF) donors (DBTTF)[3,3′-Fe(1,2-C2B9H11)2] (1) and (DBTTF)2[3,3′-Cr(1,2-C2B9H11)2] (2) were synthesized and their crystal structures were determined by single crystal X-ray diffractions. The electric conductivity measurements revealed that these compounds are semiconductors at room temperature and the conductivity of (DBTTF)2[3,3′-Cr(1,2-C2B9H11)2] is ~500 times higher than that of its BEDT-TTF analogue.

A new radical cation salt of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iron(III) bis(1,2-dicarbollide) 8,8´-dichloro derivatives, that is (BEDT-TTF)2[8,8´-Cl2-3,3´-Fe-(1,2-C2B9H10)2], was synthesized. Its electroconducting and magnetic characteristics were studied, molecular and crystal structures were determined. The electroconductivity of crystals at room temperature was σ293 ~5 Ω–1 cm–1, which is close to the corresponding value for the salt of cobalt bis(1,2-dicarbollide) dichloro derivative and is considerably higher than the electroconductivity of a similar salt of unsubstituted iron bis(1,2-dicarbollide). The measurements of magnetic susceptibility at 2—300 K showed that this salt is paramagnetic.

Radical cation salts based on derivatives of tetrathiafulvalene and sandwiched transition metal bis(dicarbollide) anions are of great interest in the development of new molecular conducting materials. The data on their synthesis, crystal structure, and electrical and magnetic properties were reviewed. The effect of various substituents in the metallacarborane anion on the structure and physical properties of their tetrathiafulvalene-based radical cation salts was analyzed. Relationships between the crystal structure and properties of the tetrathiafulvalene-based radical cation salts containing sandwiched transition metal bis(1,2-dicarbollide) anions are discussed.

Tautomeric forms of 3-formyl-4-hydroxycoumarin arylhydrazones were studied by 1H and 13C NMR spectroscopy, as well as X-ray structural analysis. These compounds were shown to exist primarily in the 4-hydroxycoumarin form both in DMSO solution, as well as in gas phase; the chroman-2,4-dione form was a minor component. According to X-ray structural analysis data, solid 3-formyl-4-hydroxycoumarin phenylhydrazone exists in the 4-hydroxycoumarin form.

Four new [(NHC)RhCl(COD)] (NHC = perimidin-2-ylidene; COD = 1,5-cyclooctadiene) rhodium complexes (4a–c and 5a) have been prepared by the reaction of [Rh(μ-OMe)(COD)]2 with perimidinium bromides (2a–c and 3a). The halogen exchange, abstracted from 1,2-dichloroethane was observed during the reaction and [(NHC)RhCl(COD)] complexes were obtained instead of [(NHC)RhBr(COD)]. All ligand precursors and complexes have been fully characterized by 1H, 13C NMR, IR spectroscopy, elemental analysis and mass spectroscopy. X-ray diffraction studies on single crystals of 4a and 5a confirm the square planar geometry. The υ(CO) values of [(NHC)RhCl(CO)2] complexes (6a–c and 7a) revealed that the NHC ligands are not good σ-donors. Transfer hydrogenation (TH) reaction of aliphatic and aromatic ketones has been comparatively studied by using complexes 4a–c and 5a as catalysts.

Radical cation salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and bis(methylenedithio)tetrathiafulvalene (BMDT-TTF) with the 8,8′-dichloro derivative of cobalt bis(1,2-dicarbollide) (BEDT-TTF)2[8,8′-Cl2-3,3′-Co(1,2-C2B9H10)2] (1) and (BMDT-TTF)4[8,8′-Cl2-3,3′-Co(1,2-C2B9H10)2] (2) were synthesized and their crystal structures and electrocon-ducting properties were determined. The synthesized radical cation salts are semiconductors with the conductivity σ293 = 1.5 and 2.0 Ohm−1 cm−1, respectively. A decrease in the size of the substituent in a series of (BEDT-TTF)2[8,8′-X2-3,3′-Co(1,2-C2B9H10)2] and (BMDT-TTF)4[8,8′-X2-3,3′-Co(1,2-C2B9H10)2] (X = I, Br, Cl) results in the compression of the anion sublattice of the crystal and compaction of the radical cation packing of the conducting layer, which, in turn, increases the conductivity of the crystals.

The oxidative cross-coupling between 4-hydroxy-6-methyl-2-pyrone or 3-hydroxy-2-methyl-4-pyrone and secondary phosphine chalcogenides proceeds in CCl4/Et3N under mild conditions (20–52 °С, 0.75–10 h) through the hydroxyl group to give O-(6-methyl-2-oxo-2H-pyran-4-yl) diorganylphosphinochalcogenoates or O-(2-methyl-4-oxo-4H-pyran-3-yl) diorganylphosphinochalcogenoates, in high yields.

Tris(2-pyridyl)phosphine chalcogenides Py3P=X (X = O, S, Se) react with PdCl2 or Li2PdCl4 to give the chelate complexes cis-[Pd(N,N’-Py3P=X)Cl2] in which PdII ion is square-planar coordinated to two pyridine nitrogen atoms of the ligand (κ2-N,N’).

Genuine organic anion-radical salt (N-Me-2,6-di-Me–Py)(TCNQ) 2 with pyridine-based cation was synthesized and its crystal structure was resolved. The DC magnetic susceptibility was measured in temperature range from 2 K to 300 K in magnetic fields 10 mT, 100 mT and 1 T. Zero field cooling (ZFC) and field cooling (FC) modes were used. The results were studied in terms of one-dimensional magnetic models and we have found that the most suitable of them is an antiferromagnetic linear Heisenberg S = 1/2 system with small amount of free spins. An additional peak observed at low temperatures can be explained by an interchain coupling between free chain-end spins.

New radical cation salts (BEDT-TTF)2[anti-7,7′:8,8′-bis(dithio)bis(7,8-dicarba-undecaborate)] and (TMTTF)2[anti-7,7′:8,8′-bis(dithio)bis(7,8-dicarbaundecaborate)] were obtained by electrocrystallization from solution of bis(ortho-carboranyl-1,2-dithiolate)cobalt(II) complex (Me4N)2[Co(1,2-S2C2B10H10)2] and BEDT-TTF or TMTTF, respectively, in acetonitrile – 1,1,2-thrichloroethane. The process is accompanied with the complex demetallation, partial deboronation of the carborane cage and oxidation of dithiolate to cyclic bis(disulfide). X-ray crystal structures and electrical conductivities of the compounds synthesized were determined.

A technique is proposed for directed synthesis of 6,11-dichloro-9-dimethylthio-7,8-dicarba-nido-undecaborane [6,11-Cl2-9-SMe2-7,8-C2B9H9]. Single-crystal X-ray diffraction is used to identify the molecular and crystal structure of the compound.

Radical cation salts based on derivatives of tetrathiafulvalene and sandwiched transition metal bis(dicarbollide) anions are of great interest in the development of new molecular conducting materials. The data on their synthesis, crystal structure, and electrical and magnetic properties were reviewed. The effect of various substituents in the metallacarborane anion on the structure and physical properties of their tetrathiafulvalene-based radical cation salts was analyzed. Relationships between the crystal structure and properties of the tetrathiafulvalene-based radical cation salts containing sandwiched transition metal bis(1,2-dicarbollide) anions are discussed.

Imidazo(4,5-b)pyridines are readily annelated (45-50 o C, 24-30 h, MeCN) with cyanoacetylenic tertiary �-alcohols to give stereoselectively functionalized 1,3-oxazolo(3,2-a)imidazo(4,5- b)pyridines in 50-88% yields. The adducts undergo a facile stereoselective hydrolytic domino rearrangement to functionalized derivatives of 2,3-diaminopyridines.

Ethyl isonicotinate reacts with tertiary cyanoacetylenic alcohols under exceptionally mild conditions (room temperature, without catalyst or solvent) to afford novel polycondensed heterocyclic systems, 4,15-dioxa-7,12-diazapentacyclo[9.5.2.02,10.03,7.012,16]octadeca-8,17-dienes, in 30–68% yields. This tandem cyclization is regio- and stereospecific. Despite several asymmetric carbons (up to six) being present in the molecules, only one diastereomer is formed and both cyanomethylidene fragments possess exclusively Z-configuration. The tandem sequence includes the formation of 1,3-oxazolidino-1,2-dihydropyridines which undergo Diels–Alder cyclodimerization to give the final products.

2,3-Dihydrofuro[3,2-c]coumarin-3-one was synthesized in quantitative yield from 3-(ω-bromoacetyl)-4-hydroxycoumarin in the presence of nucleophiles (including solvents). This compound undergoes keto-enol tautomerization and easily reacts with aromatic and heteroaromatic aldehydes to form crotonization products having a Z configuration and exhibiting strong fluorescence.

Ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate, readily available from 4,5,6,7-tetrahydroindole and ethyl bromopropynoate, when treated with dichlorodicyanobenzoquinone (DDQ) in methanol affords furan-2-one–4,5,6,7-tetrahydroindole–cyclobutene sequence in a 52% yield. As kinetic and minor products, a furan-2-one isomer along with bicycloheptadienone have been either isolated or identified. The reaction has been shown to proceed via the isolable intermediate the [2+2]-cycloadduct of ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate with DDQ. Other alcohols react with the [2+2]-cycloadduct in a similar way. The effect of the alcohol structure on the products ratio has been analyzed. All the intermediates and products are formed as single diastereomer, thus indicating a concerted character of the rearrangement.

New pyridine-phosphine chalcogenide ligands, tris[2-(2-pyridyl)ethyl]phosphine sulfide 1a and tris[2-(2-pyridyl)ethyl]phosphine selenide 1b , react with zinc(II) and cadmium(II) chlorides in EtOH at room temperature to afford complexes of compositions 2ZnCl 2 ·2L ( 2 , L = 1a ) and 3CdCl 2 ·2L ( 3a , b , L = 1a , b ) in high yields. The solid-state structure of complexes 2 , 3 has been proved by X-ray analysis data. Complex 2 is a centrosymmetric dimer, where two atoms of zinc are bonded by two bridging pyridine-phosphine sulfide ligands through N atoms. Complexes 3a , b exist as polymeric chains with each bridging ligand acting as a chelate N,S- or N,Se-donor to one cadmium(II) center and as a pyridine N-donor to the next cadmium(II) center.

Substituted imidazoles (substituents are Me, Et, i-Bu, n-Hexyl, (CH2)2S–Bu-n, Ph, Bn) react smoothly (room temperature, without catalyst and solvent) with cyanoacetylenes (3-phenyl-2-propynenitrile and 4-(1-butoxyethoxy)-4-methyl-2-pentynenitrile) and aromatic or heteroaromatic aldehydes (benzaldehyde, 4-CN-benzaldehyde, pyridine-3-aldehyde) to give 3-(2-imidazolyl)-3-aryl-2-acylpropanenitriles, a hitherto unknown family of functionalized imidazole derivatives, in up to 62% yield. This three-component manifold represents a novel C(2)-functionalization of the imidazole nucleus involving zwitterionic, carbene and enol ether intermediates. Unlike the analogous reaction with aliphatic aldehydes, which gives enol ethers, in this case the latter undergo the further rearrangement to 3-(2-imidazolyl)-3-aryl-2-acylpropanenitriles.

Molecular conductors based on the 8-hydroxy cobalt bis(dicarbollide) anion, (TMTTF)[8-HO-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] (1), (BMDT-TTF)[8-HO-3,3'-Co(1,2-C2B9H10) (1',2'-C2B9H11)] (2), and (BEDT-TTF)[8-HO-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] (3), were synthesized, and their crystal structures and electrical conductivities were determined. Compounds 2 and 3 are isostructural to the corresponding radical-cation salts of the parent cobalt bis(dicarbollide). All of the radical-cation salts prepared were found to be semiconductors. The relative stability of the rotation conformers of the [8-HO-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-) anion was estimated using DFT/BP86 quantum chemical calculations.

Mechanisms of intramolecular transformations of carbanions generated from 2-aza-1,3,5-trienes by the action of potassium tert-butoxide, which could lead to homo- or heteroannular azacycloheptadienes, were studied by quantum-chemical methods in terms of the density functional theory. The corresponding gradient channels were localized for model 1-methylsulfanyl-1-(cyclopentylideneamino)- and 1-methylsulfanyl-1-(cyclohexylideneamino)buta-1,3-dien-2-ols. Analysis of the kinetic and thermodynamic parameters showed that carbanion generated from N-cyclopentylidenebuta-1,3-dien-1-amine undergoes rearrangement mainly into homoannular azacycloheptadiene and that analogous N-cyclohexylidene derivative gives rise to heteroannular isomer. The results of calculations were consistent with the experimental data.

The [2+2]-cycloadducts of DDQ and 2-ethynylpyrroles, upon ethanolysis (reflux, 15 min or room temperature, 24 h), rearrange from bicyclo[4.2.0]octadienediones to bicyclo[3.2.0]heptadienone- and cyclobutenyl-dihydrofuranone moieties in 55–83% yields, the former rearrangement being the major direction. Benzoquinone ring cleavage is regioselective to afford mostly bicyclo[3.2.0]heptadienone-pyrrole ensembles (85–90% selectivity) in 39–78% yields. The only exception is when the starting compounds contain an ethoxycarbonyl substituent and the pyrrole counterpart is a 4,5,6,7-tetrahydroindole fragment. In this case, the ratio of the rearrangement products is 1:1.2 in a total yield of 83%. An important feature of the dihydrofuranone pathway rearrangement is its 100% diastereoselectivity.

According to 1? and 13? NMR data, enamines of 3-formyl-4-hydroxycoumarin exist in the keto enamine tautomeric form and undergo Z/E-isomerization around the C=C bond in CDCl3, DMSO-d6, and CD3OD at room temperature. The activation energies of ?/Z-isomerization were measured experimentally and calculated by the B3LYP/6-311++G(d,p) method. An X-ray diffraction study showed that 3-(benzyliminomethyl)chromane-2,4-dione in the crystalline state exists as a mixture of two keto enamine isomers.

A 1D heterometallic Cr2/Ag2 polymer formulated as {[Ag(μ-H2O)Ag(nta)Cr(μ-OH)(μ-AcO,O′)Cr(nta)]·H2O}n (1) (H3nta = nitrilotriacetic acid) has been prepared and structurally characterized. {Cr(μ-OH)(μ-OAc)Cr} dimeric units containing two different bridging ligands, hydroxo and acetate groups are coordinated to six Ag atoms forming the 1D network. The temperature dependence of magnetic susceptibility for 1 which was fitted with an isotropic Hamiltonian including biquadratic exchange parameters, yielded antiferromagnetic interaction parameters (J = −8.5(1), j = −0.50(7) cm−1 g = 2.0).

Methyl substituted 2-phenyldiazenyl-N-vinylpyrroles when refluxed in toluene in the airflow are unexpectedly oxidized at their methyl substituents retaining the pyrrole and N-vinyl moieties intact. The major products of the autooxidation are hydroxyalkyl derivatives (yield up to 60%), the corresponding aldehydes being formed in minor quantities (yield up to 21%). This non- typical oxidation of substituted pyrroles opens a conceptually novel approach to functionalization of phenyldiazenylpyrrole dyes.

The radical cation salts of tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iodo derivatives of cobalt bis(dicarbollide), (TTF)[9,9′,12,12′-I4-3,3′-Co(1,2-C2B9H9)2] and (BEDT-TTF)[9,9′(12′)-I2-3,3′-Co(1,2-C2B9H10)2], respectively, were synthesized and their crystal structures were determined. The introduction of iodine atoms into the lower rim of the dicarbollide ligands, unlike the substitution at the upper rim, leads to insignificant changes in the crystal structure and the conductivity of the radical cation salts compared to the analogous salts based on unsubstituted cobalt bis(dicarbollide).