The crystal structure of LaIr4B4, ThOs4B4, ThIr4B4 (NdCo4B4-type) and URu4B4, UOs4B4 (LuRu4B4-type)

The crystal structure of LaIr₄B₄ has been refined from single crystal counter data. LaIr₄B₄ is tetragonal,P4₂/n,Z=2, isotypic with NdCo₄B₄, |F|/|F _o|=0.039 for 312 independent reflections [|F _o|>2 (F _o)]. ThIr₄B₄ and ThOs₄B₄ also belong to the NdCo₄B₄-type structure. URu₄B₄ and UOs₄B₄ were found to crystallize with LuRu₄B₄-type structure. The crystal chemistry of (RE)T ₄B₄-phases is discussed and simple geometric relations are shown to exist between them.Dedicated to Prof.B. T. Matthias in celebration of his 60th birthday.     

Synthesis of 4H-pyrazolo- and 4H-pyrrolophenothiazin-4-one derivatives

5-Methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones were condensed with 2-aminobenzenethiol or 6-substituted-3-aminopyridine-2(1H)thiones 4 to produce a new type of 5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-ones or 8-substituted-7-aza-5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-one derivatives. From 6-bromo-2,5-dimethyl-1,3-diphenyl-2H-isoindole-4,7-dione and 4 8-substituted-7-aza-2,5-dimethyl-1,3-diphenyl-4H-pyrrolophenothiazin-4-one derivatives were also prepared.     

Studies on Li2SO4-MgSO4 and Li2SO4-Li4SiO4 systems

The phase equilibria as well as the properties and crystal structures of the compounds formed in both Li₂SO₄-MgSO₄ and Li₂SO₄-Li₄SiO₄ systems have been studied by means of x-ray diffraction technique (at high and room temperatures) as well as by the thermal analyses (DTA, DSC, TGA, etc.). In Li₂SO₄-MgSO₄ system there exists a compound Mg₄Li₂(SO₄)₅ formed by peritectic reaction at 840°C and decomposed at 105°C into the Li₂SO₄-base solid solution and MgSO₄ · Mg₄Li₂(SO₄)₅ and Li₂SO₄-base solid solution conduct an eutectic reaction at 663°C with the composition of eutectic point lying in 22 mol% MgSO₄. The solubility of MgSO₄ in Li₂SO₄ is a little smaller than 10 mol% while at the same time the Li₂SO₄ phase transition temperature decreases from 574 to 560°C On the other hand, no noticeable solid solubility of Li₂SO₄ in MgSO₄ has been observed. The reaction is an endothermal one and its heat of formation is 2.57 kJ/mol. The activation energy of the reaction calculated by thermal peak displacement method at various heating rates is 173.5 kJ/mol (1.80 ev). The crystal Mg₄Li₂(SO₄)₅ belongs to orthorhombic system with lattice parameters at 180°C: a = 8.577, b=8.741, c= 11.918 Å. The space group seems to be either P222 or P mmm. Assuming that there are two formula units in a unit cell, the density calculated is then 2.20 g/cm³ very close to that of Li₂SO₄ or MgSO₄. Meanwhile, in Li₂SO₄-Li₄SiO₄ system a new phase Li_8-2x(SiO₄)_8-x(SO₄)_x is formed by peritectic reaction at 953°C with a range of composition x=0.96 ?0.58. The crystal belongs to ortho-rhombic system with lattice parameters at x=0.8: a = 5.002, b= 6.173 and c=10.608Å. The density observed is 2.31 g/cm³ and there are 2 formula units in an unit cell. It is shown from the measurements of piezoelectric and laser SHG coefficients of the crystal that the crystal posseses a symmetrical center with the space group belonging to P mmn. The lattice parameter c has a maximum at x=0.8. In the air Li_8-2x(SiO₄)_2-x(SO₄)_x can absorb 7.6 wt% water vapour and other gases which can only be desorbed by heating it at a temperature above 350°C. Neither absorption nor desorbtion can change its crystal structure, a characteristic similar to that of zeolite molecular sieve. The dewater activation energy of Li_8-2x(SiO₄)_2-x(SO₄)_x is 171.5 kJ/mol. Li_8-2x(SiO₄)_2-x(SO₄)_x and Li₄SO₄ bring about an eutectic reaction at 823°C with its eutectic composition being 12 mol% Li₄SiO₄. No observable solubility of Li₄SiO₄ in Li₃SO₄ has been noticed. The solubility of Li₂SO₄ in Li₄SiO₄ is approximately equal to 5 mol%. With Li₂SO₄ being dissolved in, the phase transition temperature of Li₄SiO₄ is decreased. After being fused, the specimens Li₃SO₄-MgSO₄ and Li₂SO₄-Li₄SiO₄ are cooled at a rate of 10°C/min, their metastable eutectic systems are resulted respectively.     

Synthesis and Reactions of 4-cis- and 4-trans-Hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines

By treating 2e-methyl-4-oxo-trans-decahydroquinoline with lithium acetylide a mixture of stereoisomeric 4-cis-hydroxy-2e-methyl- and 4-trans-hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines was obtained in 3:2 ratio. Their reaction with acetonitrile in the presence of sulfuric acid (Ritter's reaction) results in a mixture of stereoisomeric 4-cis-acetylamino-2e-methyl- and 4-trans-acetylamino-2e-methyl-4-ethynyl-trans-decahydroquinolines in the same ratio. The ethynyl group of alcohols synthesized is not hydrated under conditions of Kuchrerov's reaction. The boiling of the alcohols with formic acid furnished a mixture of 4-acetyl-2e-methyl and 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinolines in 1:7 ratio. The former of these compounds under conditions of Ritter's reaction yielded a mixture (1:1.4) of stereoisomeric 4-acetyl-4-trans-acetylamino- and 4-acetyl-4-cis-acetylamino-2e-methyl-trans-decahydroquinolines. From 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinoline under the same conditions were obtained both already mentioned stereoisomeric 4-acetylamino-2e-methyl-4-ethynyl-decahydroquinolines (53% of cis-isomer and 35% of trans-isomer in the mixture) and 4-acetyl-4-acetylamino-2e-methyldecahydroquinolines (7% of cis-isomer and 5% of trans-isomer).     

Electronic structures of the boron cage molecules B4H4, B4Cl4 and B4F4

Ab initio calculations have been performed on B₄H₄, B₄Cl₄ and B₄F₄ in order to aid our understanding of the bonding in these compounds, which is presumably based on a tetrahedral boron cage. This cage has only 8 electrons and so is less than that expected on the basis of the usual framework electron counting rules. Basis sets with polarisation functions were used at the SCF, CI and CPF levels of theory to confirm that the T _d structures are indeed more stable than the D _4h ones. Davidson-Roby population analyses were able to show that many factors, including 3-centre 2-electron bonding and backbonding from the ligand to the boron cage, are of importance in determining the relative stability of the three compounds, of which B₄Cl₄ is the only one that has yet been observed experimentally.     

2-Trif luoromethyl-4H-thiochromen-4-one and 2-trif luoromethyl-4H-thiochromene-4-thione: Synthesis and reactivities

2-Trifluoromethyl-4H-thiochromene-4-thione obtained from 2-trifluoromethyl-4H-thiochromen-4-one and P₂S₅ reacts with aromatic amines, hydrazine hydrate, phenylhydrazine, and hydroxylamine at the C(4) atom of the chromene ring to give the corresponding anils, azine, hydrazones, and oxime of thiochromone. 2-Trifluoromethyl-4H-thiochromen-4-one is oxidized by hydrogen peroxide in AcOH into 4-oxo-2-trifluoromethyl-4H-thiochromene 1,1-dioxide and reduced by NaBH₄ to 2-trifluoromethyl-4H-thiochromen-4-ol or cis-2-(trifluoromethyl)thiochroman-4-ol. When treated with hydrazine hydrate, thiochromen-4-one gives 3(5)-(2-mercaptophenyl)-5(3)-trifluoromethylpyrazole. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 504–509, March, 2006.     

Bildung von 5,6-Dihydro-1,3(4H)-thiazin-4-carbonsäure-estern aus 4-Allyl-1,3-thiazol-5(4H)-onen

Formation of Methyl 5,6-Dihydro-l, 3(4H)-thiazine-4-carboxyiates from 4-Allyl-l, 3-thiazol-5(4H)-ones . The reaction of N-[1-(N, N-dimethylthiocarbamoyl)-1-methyl-3-butenyl]benzamid ( 1 ) with HCl or TsOH in MeCN or toluene yields a mixture of 4-allyl-4-methyl-2-phenyl-1,3-thiazol-5(4H)-one ( 5a ) and allyl 4-methyl-2-phenyl-1,3-thiazol-2-yl sulfide ( 11 ; Scheme 3). Most probably, the corresponding 1,3-oxazol-5(4H)-thiones B are intermediates in this reaction. With HCl in MeOH, 1 is transformed into methyl 5,6-dihydro-4,6-dimethyl-2-phenyl-1,3(4H)-thiazine-4-carboxylate ( 12a ). The same product 12a is formed on treatment of the 1,3-thiazol-5(4H)-one 5a with HCl in MeOH (Scheme 4). It is shown that the latter reaction type is common for 4-allyl-substituted 1,3-thiazol-5(4H)-ones.     

UCr4C4 with filled MoNi4 type structure

The title compound was prepared by arc melting coldpressed pellets of the elemental components with subsequent annealing at both 800°C or 1100°C. UCr₄C₄ crystallizes tetragonal, space group I4/m,a=0.79363 (4) nm,c=0.30754 (3) nm,V=0.19370 nm³ withZ=2 formula units per cell. The structure was determined from single-crystal X-ray data and refined to a residual ofR=0.027 for 16 variable parameters and 279 structure factors. The positions of the metal atoms correspond to those of the MoNi₄ type structure. The carbon atoms occupy octahedral voids formed by four chromium and two adjacent uranium atoms. Chemical bonding in UCr₄C₄ and in other interstitial compounds is briefly discussed. The average valence electron number of the metal atoms is usually greater for the unfilled (host) structure than for the corresponding filled structure.Dedicated to Prof. Dr.Kurt Komarek and to Prof. Dr.Adolf Neckel on the occasion of their 60th birthdays.     

Synthesis and rearrangement of 4-imino-4H-3,1-benzoxazines

Summary N-Acylanthranilamides react with dibromotriphenylphosphorane in the presence of triethylamine as HBr captor to give 4-imino-4H-3,1-benzoxazines in good yields. If the reaction is carried out without acid acceptor, N-acetylanthranilamides yield 2-methyl-4-quinazolones, whereas N-benzoylanthranilamides give 2-phenyl-4-imino-4H-3,1-benzoxazines. It has also been found that 2-methyl-4-imino-4H-3,1-benzoxazines rearrange under the influence of HCl or HBr into the respective 2-methyl-4-quinazolones; 2-phenyl-4-imino-4H-3,1-benzoxazines, however, do not undergo such a rearrangement.

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Synthese und Umlagerung von 4-Imino-4H-3,1-benzoxazinen

Zusammenfassung Die Umsetzung von N-Acyl-anthranilsäure-amiden mit Triphenyldibromphosphoran in Gegenwart von Triethylamin als HBr-Akzeptor führt mit guten Ausbeuten zu 4-Imino-4H-3,1-benzoxazinen. Wird die Reaktion ohne säurebindendes Mittel durchgeführt, dann entstehen aus N-Acetyl-anthranilsäure-amiden 2-Methylchinazolone-4, jedoch erhält man aus N-Benzoylanthranilsäure-amiden 2-Phenyl-4-imino-4H-3,1-benzoxazine. 2-Methyl-4-imino-4H-3,1-benzoxazine erleiden unter dem Einfluß von HBr oder HCl eine Umlagerung in entsprechende 2-Methylchinazolone-4, während 2-Phenyl-4-imino-4H-3,1-benzoxazine zu einer solchen Umlagerung nicht befähigt sind.

     

The preparation of 3,5-disubstituted tetrahydro-4H-1,3,5-oxadiazine-4-thiones,tetrahydro-4H-1,3,5-thiadiazin-4-ones,and tetrahydro-4H-1,3,5-thiadiazine-4-thiones

The reaction of 1,3-disubstituted thioureas with formaldehyde under acidic conditions with removal of water yielded 3,5-disubstituted tetrahydro-4H-1,3,5-oxadiazine-4-thiones. When hydrogen sulfide was bubbled through the reaction mixture, the corresponding tetrahydro-4H-1,3,5-thiadiazine-4-thiones were formed. Similarly, starting from 1,3-disubstituted ureas, a number of tetrahydro-4H-1,3,5-thiadiazine-4-ones were prepared. The latter compounds were also oxidized to the corresponding sulfoxides and sulfones.     

Synthese der isomeren 3, 4-Dimethyl-4-phenyl-3, 4-dihydro-carbostyrile

Cyclisation of 2-methyl-3-phenyl-but-3-en-anilide (III) with polyphosphoric acid gave cis-3, 4-dimethyl-4-phenyl-3, 4-dihydro-carbostyril (VII) in 61% yield together with a small amount of 2, 3-dimethylindenone (VIII), whereas with AlCl₃ a phenyl group was split off to give 3, 4-dimethylcarbostyril (VI). The anilide III isomerises to cis- and trans-2, 3-dimethyl-cinnam-anilide (IV resp. V) under basic conditions. The anilides IV and V gave only small yields of the dihydrocarbostyril VII with polyphosphoric acid. Chlorination of VII in position 3 using PCl₅ yielded IX which, on splitting out HCl, gave 3-methylene-4-methyl-4-phenyl-3, 4-dihydro-carbostyril (X). X was converted to trans-3, 4-dimethyl-4-phenyl-3, 4-dihydro-carbostyril (XI) by catalytic hydrogenation.     

Dielectric Properties of 4-(2,3-Epoxypropoxy)- and 4-Propoxy-4'-alkoxyazoxybenzenes

The temperature dependences of the dielectric permittivity of 4-(2,3-epoxypropoxy)-4'-alkoxyazoxybenzenes (n = 1-10) and 4-propoxy-4'-alkoxyazoxybenzenes (n = 1-10) with mesomorphic properties were measured by dielectrometry. The introductrion of the terminal epoxy group increases the dielectric permittivity and its anisotropy. The dipole moments of molecules of 4-(2,3-epoxypropoxy)-4'-alkoxyazoxybenzenes (n = 1-10) and 4-propoxy-4'-alkoxyazoxybenzenes (n = 1-10) were determined by the second Debye method. The epoxy-substituted azoxybenzenes have higher dipole moments than their structural analogs.     

Halogenide der Seltenerdmetalle Ln4X5Z. Teil 3: Das Chlorid La4Cl5B4 – Präparation,Struktur und Verwandtschaft zu La4Br5B4, La4I5B4

Rare Earth Halides Ln₄X₅Z. Part 3: The Chloride La₄Cl₅B₄ – Preparation, Structure, and Relation to La₄Br₅B₄, La₄I₅B₄ La₄Cl₅B₄ is synthesized by reaction of LaCl₃, La metal and boron in sealed Ta containers at 1050 °C < T < 1350 °C. It crystallizes in the monoclinic space group C2/m with a = 16.484(3) Å, b = 4.263(1) Å, c = 9.276(2) Å and β = 120.06(3)°. Ce₄Cl₅B₄ is isotypic, a = 16.391(3) Å, b = 4.251(1) Å, c = 9.180(2) Å and β = 120.20(3)°. The La atoms form strings of trans-edge shared La octahedra, and the B atoms inside the strings form B₄-rhomboids, which are condensed to chains via opposite corners. The Cl atoms interconnect the channels according to La₂La_4/2Clⁱ⁻ⁱ_6/2Cl^i−a_2/2Cl^a−i_2/2. The crystal structures of the bromide and the iodide are comparabel, however, the interconnection of the strings is different in the three structure types, as 14 Cl, 13 Br and 12 I atoms surround the La₆ octahedra.     

Synthesis of 4-(4-phenyl-3-pyrazolyl)-4H-1,2,4-triazoles

4-(4-PhenyI-3-pyrazolyl)-4H-1,2,4-triazoles and 4-phenyl-5-(4H-1,2,4-triazol4-yl)-3-pyrazolols were prepared by the reaction of formylhydrazine on α-phenyl-α-cyanoacetaldehydes and ethyl α-phenyl-α-cyanoacetates.     

The synthesis of 4-substituted-4H-1,2,4-triazole-3-thiols and 3-methylthio-4-substituted-4H,2,4-triazoles

The synthesis of 4-substituted-4H-1,2,4-triazole-3-thiols and 3-methylthio-4-substituted-4H-1,2,4-triazoles by the condensation of 4-substituted-3-thiosemicarbazides with dimethylformamide dimethyl acetal or dimethylacetamide dimethyl acetal is described. A discussion of the mechanistic pathway is included.     

Rubidium stannate(IV), Rb4SnO4

The title compound, tetra­rubidium tetra­oxa­tin(IV), crystallizes with the Na₄CoO₄ structure type, showing discrete SnO₄^4? anions as main building blocks. The structure is thus isotypic with a series of corresponding A₄MO₄ compounds(A = alkali metal and M = group IV element).     

Synthesis of succinic acid 12α-deoxoartemisinyl ester 4′-O-demethyl-4β-(4″-nitroanilino)-4-desoxypodophyllotoxin

The succinic acid 12α-deoxoartemisinyl ester 4′-O-demethyl-4-β-(4″-nitroanilino)-4-desoxypodophyllotoxin was synthesized for the first time. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 442–443, September–October, 2007.     

Synthesis of 5,6-dihydro-4H-thiopyran-4-ones

The anions of 1,4-diaryl-3-buten-2-ones 1 reacts with arylisothiocyanates, yielding intermediates 4 which can ring close to 5,6-dihydro-4H-thiopyran-4-ones 5 . Under similar reaction conditions ethyl 3-oxo-4-pentenoates 7 gives the 6-spiropyrans 9 . Methylation of 3 gives the S-methylated open form 6 .     

(CuBr)3P4Se4: A Low Symmetric Variant of the (CuI)3P4Se4 Structure Type

Bright orange (CuBr)₃P₄Se₄ is obtained from the reaction of CuBr, P, and Se in stoichiometric amounts (CuBr : P : Se = 3 : 4 : 4). The composition and the crystal structure of the compound were determined from single crystal X‐ray diffraction data. Lattice constants are a = 33.627(2) Å, b = 6.402(1) Å, c = 19.059(1) Å, β = 90.19(3) °, V = 4103.2(3) ų, and Z = 12. The compound crystallizes in a structure that is related to (CuI)₃P₄Se₄. Cages of β‐P₄Se₄ are stacked along the b‐axis and are separated by columns of copper(I) bromide. However, the coordination of the β‐P₄Se₄ cage molecules to the copper atoms in the CuBr columns in (CuBr)₃P₄Se₄ is quite different from (CuI)₃P₄Se₄. The monoclinic compound (space group: P2₁, no. 4) has an almost orthorhombic metric in combination with a threefold superstructure in [100]. Structural aspects of (CuBr)₃P₄Se₄ are discussed with respect to the heavier homologue (CuI)₃P₄Se₄.     

Reactions of 4-cyano- and 4-methylimidazoles with isocyanates

4-Cyano- and 4-methylimidazoles reacted with methyl and aryl isocyanates to give exclusively 1-(substituted carbamoyl)-4-cyano- and 4-methylimidazoles, respectively. Refluxing of 1-carbamoyl-4-methylimidazoles in nitrobenzene yielded 2-carbamoyl-4-methylimidazoles through a known migration, whereas the 4-cyano analogues could not be caused to migrate. On the other hand, the treatment of 4-cyano-1-(methylcarbamoyl)imidazole with methyl isocyanate under the basic conditions resulted in the formation of 2-methyl-1-(methylcarbamoylimino)-2, 3-dihydro-1H-imidazo[1, 5-c]imidazol-3-one which must be formed via the migration of the carbamoyl group to another nitrogen followed by the intramolecular cyclization of the newly introduced carbamoyl group with its viccyano group.