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It is experimentally found that in the Ni54Fe20-xCoxGa26 ferromagnetic shape memory alloys, Co variation from 0 to 9 at.% leads to: (i) almost linear change of martensitic transformation temperatures from 270 °C to 120 °C; (ii) a non-monotonous change of the Curie temperature, and (iii) a linear decrease of saturation magnetization from 60 to 43 Am2/kg. The selected alloys grown as single crystals have been (magneto-)mechanically tested. The superelastic effect has been measured to be about 4%. The magneto-strain shows a training effect which is an evidence of the effect of magnetic-field-induced twin-boundary motion.

The title compound, C 34 H 52 O 4 , consists of five six-membered rings. All of the rings except the one with two double bonds exist in chair form. The ring with two double bonds is almost planar with a mean deviation from planarity of only 0.03 A.

Iron fluorides with tetragonal tungsten bronze (TTB) structure, having general formula of ${\text{K}}_{x}{\text{Fe}}_{x}^{\text{II}}{\text{Fe}}_{1\ensuremath{-}x}^{\text{III}}{\text{F}}_{3}$ with $0.4lxl0.6$, are possible candidates for complete multiferroism (elastic, electric, and magnetic orders) coupled with charge ordering phenomena. Following the indication of a previous general work, we concentrated our attention on the potassium rich region of these bronzes where an orthorhombic distortion of the fundamental TTB structure takes place. We tried to define the complex phase diagram of ${\text{K}}_{0.6}{\text{FeF}}_{3}$, involving the different ordering phenomena in the range of 5\char21{}600 K, by using a series of characterization techniques such as transmission electron microscopy, x-ray and neutron diffractions, and magnetic measurements. The results revealed the coexistence of all these orders below the magnetic transition occurring at 118 K, showing the unique behavior of a system that can be considered a model for multiferroism.

It is well known that the composition of ferromagnetic shape memory Ni–Mn–Ga Heusler alloys determines both temperature of martensitic transformations and the structure type of the product phase. In the present work we focused our attention on the structural study of the so-called “5M” modulated structure. In particular, the structure of Ni1.95Mn1.19Ga0.86 martensitic phase is analysed by powder X-ray diffraction (PXRD) and compared with that of the stoichiometric Ni2MnGa martensite. The study of the diffraction data reveals the occurrence of commensurate (C) structural modulation in Ni1.95Mn1.19Ga0.86; this contrasts with Ni2MnGa, where an incommensurate (IC) structural modulation was evident. The two phases also differ in the symmetry of the fundamental martensitic lattice. In fact, the incommensurate modulation is related to an orthorhombic basic structure, while the commensurate variant presents a monoclinic symmetry. The commensurate modulated structure has been investigated by using the superspace approach already adopted to solve the structure of Ni2MnGa martensite. The structure has been determined by Rietveld refinement of PXRD data.

The structural properties of BiMn$O_3$ were determined from neutron powder diffraction data as a function of temperature and magnetic field. The structure at all temperatures was found to be centrosymmetric with space group $C2/c$, which is incompatible with ferroelectricity. At T$_C\simeq 100 K$, we observed the onset of a large magnetoelastic strain, proportional to the square of the magnetization. We interpret this structural rearrangement, together with the previously observed magnetodielectric anomalies, as due to the need to optimize the partially frustrated magnetic interactions., Comment: 4 pages, 4 figures

4 tables, 5 figures.-- et al., The ferromagnetic shape memory (MSM) alloy Ni2MnGa undergoes a martensitic transformation (MT) at T=220 K on cooling. The structure of this phase is studied by powder X-ray diffraction experiment. The analysis of the experimental data combined with the huge information reported in literature allowed to conclude that the Ni2MnGa martensite shows an incommensurate modulated structure closely related to a five-fold layered superstructure. The symmetry of the basic structure is found to be orthorhombic. The structure is refined by Rietveld method with superspace group Immm(00γ)s00 having a=4.2187(1) Å, b=5.5534(1) Å and c=4.1899(1) Å and modulation vector q=0.4248(3)c*. The results show that the modulation is mainly related to the periodic shuffling of the atomic layers perpendicular to the c-axis of the orthorhombic basic structure.

The multiferroic perovskite BiMnO3, synthesized under high-pressure conditions, decomposes if heated at room-pressure in the temperature range of 500-650 degrees C. Comparative studies by high-temperature X-ray diffraction, electron diffraction, thermal analysis, and magnetic investigation revealed the existence of a complex pathway to decomposition, depending on the heating rate, pressure, and atmosphere that involves different metastable phases. In particular the as-prepared monoclinic phase (I) transforms to a second monoclinic form (II) at 210 degrees C and then to an orthorhombic phase (III) at 490 degrees C. These phase transitions, fast and reversible, occur on heating with a drop in volume and are moved at higher temperatures when pressure is decreased. The transition from II to III, typically observed in inert atmosphere, can be detected also in air when the heating rate is kept sufficiently high. When III is heated in an oxygen-containing atmosphere a slow irreversible transition to variants IV and then V takes place with kinetics depending on temperature, heating rate, and oxygen partial pressure. Both IV and V are oxidized ferromagnetic phases containing Mn4+ characterized by a modulated structure based on fundamental triclinic perovskite cells. Their magnetic behavior shows a strong analogy with thin films of BiMnO3, suggesting for the latter an oxidized nature and for the former a possible multiferroic behavior.

N,N-Dimethyl-p-nitrosoaniline reacts with benzoyl chloride affording a complex salt containing a cation, a hybrid between a nitrenium ion and an iminium ion. The salt reacts with nucleophiles (indoles, indolizines) yielding compounds characterized by a new carbon-nitrogen bond, derived from the nitrenium ion form. According to the type of nucleophile, the reaction, to differing extents, is in competition with an electron transfer process which leads to the formation of the dimer of the nucleophile and of the azoxy corresponding to the N,N-dimethyl-p-nitrosoaniline. In one of the reactions studied, a chlorinated azoxy derivative was also isolated, and its structure was elucidated by X-ray analysis.

WOS: 000362562100110 The applicability of the magnetic shape memory effect in Ni-Mn-based martensitic Heusler alloys is closely related to the nature of the crystallographically modulated martensite phase in these materials. We study the properties of modulated phases as a function of temperature and composition in three magnetic shape memory alloys Ni49.8Mn25.0Ga25.2, Ni49.8Mn27.1Ga23.1 and Ni49.5Mn28.6Ga21.9. The effect of substituting Ga for Mn leads to an anisotropic expansion of the lattice, where the b-parameter of the 5M modulated structure increases and the a and c-parameters decrease with increasing Ga concentration. The modulation vector is found to be both temperature and composition dependent. The size of the modulation vector corresponds to an incommensurate structure for Ni49.8Mn25.0Ga25.2 at all temperatures. For the other samples the modulation is incommensurate at low temperatures but reaches a commensurate value of q approximate to 0.400 close to room temperature. The results show that commensurateness of the 5M modulated structure is a special case of incommensurate 5M at a particular temperature. (C) 2015 Author(s). Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG) [SPP 1599] Work supported by the Deutsche Forschungsgemeinschaft (SPP 1599).

The crystal structure of the NdGe 1.66 compound [ I 4 1 / amd space group, a =4.180(1) A, c =13.980(3) A, V =244.26 A 3 , ρ =8.953 g/cm 3 , μ =41.37 mm −1 , R =0.0341 for 106 reflections with I 0 >4 σ ( I 0 )] was determined from single crystal X-ray diffraction (using the Laue, rotation, Weissenberg methods, a Philips PW 1100 diffractometer). The compound was found to crystallize with an α-ThSi 2 structure type.

In the title cocrystal, trimethoprim maleate [2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium maleate], C(14)H(19)N(4)O(3)(+).C(4)H(3)O(4)(-), the trimethoprim molecule is protonated at N1. The carboxyl group of the maleate ion makes a specific double hydrogen bond of type N-H.O with the 2-amino group and the protonated N1 atom of the trimethoprim cation which is similar to the carboxylate-trimethoprim cation interaction observed in the complex of dihydrofolate reductase with trimethoprim. The pyrimidine moieties of trimethoprim cations are centrosymmetrically paired through a pair of N-H.N hydrogen bonds involving the 4-amino group and the pyridinium N3 atom of a symmetry-related molecule. One of the O atoms at the maleate carboxylate group bridges the 2-amino and 4-amino groups on either side of the paired trimethoprim cations. The other O atom of the carboxylate group forms an intramolecular O-H.O hydrogen bond with the carboxyl group. These characteristic hydrogen bonds result in infinite two-dimensional aggregation of rings into a supramolecular ladder, which is further crosslinked through weak C-H.O interactions with methoxy groups of neighbouring trimethoprim molecules to form a layered structure.

The triclinic crystal structure of f-Bi8Pb5O17, a ionic fast conductor material, has been determined by the synergy of both electron and powder X-ray crystallography. The heavy atom positions were found by direct methods on electron diAraction data and the structure was completed by iterative use of a priori information in direct methods and diAerence Fourier maps on both types of data. Structure refinement was performed by the Rietveld method on powder X-ray data. The results suggest that f-Bi8Pb5O17 is an ordered phase, with Bi and Pb atoms occupying diAerent sites of the lattice, at variance with the other structural phases known for similar composition in the Bi‐Pb‐O phase diagram, which are solid solutions characterised by a wide compositional range. # 2000 Elsevier Science B.V. All rights reserved.

The title compound, hetisan-6,11beta,15beta-triol, C20H27NO3, is a hetisane-type diterpenoid alkaloid. It consists of six six-membered rings and two five-membered rings. The fused-ring system contains three chair, two boat, one distorted boat and two envelope conformations. Intramolecular and intermolecular hydrogen bonds are present between the O atoms, with O...O separations of 3.006 (3) and 2.743 (3) A, as well as an O...N intermolecular interaction of 2.887 (3) A.

2-Alkyl-2-phenyl-3,3-dimethylindolines, obtained by 1,2 organolithium addition to 2-phenyl-3,3-dimethyl-3H-indole, are converted into a new series of aminoxyls by oxidation with m-chloroperoxybenzoic acid. Attempts to synthesise, in a similar way, suitable precursors such as 1,2-dihydro-2-phenyl-2-alkylbenzothiazole, 1,2-dihydro-2-phenyl-2-alkylbenzoxazole and 1,2-dihydro-2-phenyl-2-alkyl-4H-3,1-benzoxazin-4-one for other new aminoxyls failed. In fact, 2-phenylbenzothiazole, 2-phenylbenzoxazole and 2-phenyl-4H-3,1-benzoxazin-4-one react with organolithium reagents affording products deriving from ring opening. Crystal structures of 2,3-dimethyl-3-phenyl-3H-indole and bis(2-triphenylmethylaminophenyl) disulfide are also described.

Samples with Bi 8 Pb 5 O 17 stoichiometry were synthesized by ceramic techniques at temperatures ranging from 200 to 640°C. Their structural properties and relative stabilities were investigated using X-ray and electron diffraction, differential scanning calorimetry, and Raman spectroscopy. The tetragonal β 2 phase is described by an incommensurately modulated structure, whose modulation depends on the firing temperature. Heat treatments in the 200–300°C range lead to the formation of a new tetragonal phase, χ , which is converted back to β 2 above 300°C. The intermediate φ phase can be obtained without the previous formation of β 2 , and its X-ray powder diffraction pattern is indexed using a triclinic cell. The present data suggest that the β 2 phase is the low-temperature polymorph of this composition.

A strong effect of pressure on magnetization and paramagnetic moment of the Co-doped Mn-rich Ni 50-x Co x Mn 25+y Ga 25-y (x = 5,7,9 and y = 5,6,7,8) Heusler alloys is presented and compared with very weak pressure sensitivity of magnetization of the stoichiometric Ni 2 MnGa alloy. The effects of both, the pressure and the magnetic field, on temperature of the structural martensitic transition in the alloys are discussed with a use of the Clausius-Clapeyron relations. An analysis of pressure and field effects provides a possibility to evaluate structural and magnetic parts of latent heat of the martensitic transitions in the studied alloys. The Curie temperature of martensite phase of the Co-rich alloys is not affected by pressure.

The magnetic, magnetocaloric and thermal characteristics have been studied in a Ni(50.3)Mn(20.8)Ga(27.6)V(1.3) ferromagnetic shape memory alloy (FSMA) transforming martensitically at around 40 K. The alloy shows first a transformation from austenite to an intermediate phase and then a partial transformation to an orthorhombic martensite, all the phases being ferromagnetically ordered. The thermomagnetization dependences enabled observation of the magnetocaloric effect in the vicinity of the martensitic transformation (MT). The Debye temperature and the density of states at the Fermi level are equal to θ(D) = (276 ± 4) K and 1.3 states/atom eV , respectively, and scarcely dependent on the magnetic field. The MT exhibited by Ni-Mn-Ga FSMAs at very low temperatures is distinctive in the sense that it is accompanied by a hardly detectable entropy change as a sign of a small driving force. The enhanced stability of the cubic phase and the low driving force of the MT stem from the reduced density of states near the Fermi level.

The synthesis, and X-ray crystal and molecular structures, of 1-phenacyl-4-(dimethylamino)pyridinium chloride and bromide monohydrates are described.

The crystal structures for two compounds were determined from single-crystal X-ray diffraction: NdRu 2 Si 2 , I4/mmm space group, a =4.189(1), c =9.754(8) A, V =171.16 A 3 , ρ =7.811 g/cm 3 , μ =240.7 cm −1 , R =0.0379 for 114 reflections and NdRh 2 (Si,Ge) 2 , I4/mmm space group, a =4.182(1), c =9.829(4) A, V =171.90 A 3 , ρ =8.708 g/cm 3 , μ =330.1 cm −1 , R =0.0533 for 152 reflections. Both structures belong to the CeGa 2 Al 2 type of structure.

Progressive substitution of La by Bi in the mixed oxides (LaBi)0.7Ca0.3MnO3 leads to great changes in the magnetic and transport properties of these compounds. From neutron diffraction experiments performed at D1B and D2B apparatus in the ILL, we have observed changes in the magnetic structure from ferromagnetic La0.65Bi0.05Ca0.3MnO3 to antiferro Bi0.7Ca0.3MnO3. The intermediate compounds show antiferromagnetism in a crystalline plane and ferromagnetism in the perpendicular direction. The distance Bi–O turns out to be shorter than the La–O due to the covalent character of the former. This can explain the increasing localization of the 3d electrons of Mn atoms and the insulating character of Bi0.7Ca0.3MnO3.

The title compound, C34H52O4, consists of five six-membered rings. Barring the two rings, with double bonds, all other rings are in chair conformations. Mean-plane and ring-puckering calculations indicate these two rings to be in distorted-chair conformations, with distortion towards the boat conformation. There are no strong hydrogen bonds and the structure is stabilized by van der Waals interactions only. The structure is compared with those reported for other triterpenes.

Thermomagnetic and magnetocaloric (MC) properties of Ni2MnGa Heusler alloys are found to be very sensitive to small composition variations. It is shown that the temperature behavior of ac susceptibility mimics that of MC properties of the samples. The coincidence of magnetic and structural transformations is found for a Mn-rich composition. As in the case of Ni-rich alloys, the magnetocaloric effect is enhanced at the transitions co-occurrence. The increase of Mn content, with respect to the stoichiometric value, rapidly decreases anisotropy field and saturation magnetization.

N,N-Dimethyl-p-nitrosoaniline reacts with benzoyl chloride affording a complex salt containing a cation, a hybrid between a nitrenium ion and an iminium ion. The salt reacts with nucleophiles (indoles, indolizines) yielding compounds characterized by a new carbon–nitrogen bond, derived from the nitrenium ion form. According to the type of nucleophile, the reaction, to differing extents, is in competition with an electron transfer process which leads to the formation of the dimer of the nucleophile and of the azoxy corresponding to the N,N-dimethyl-p-nitrosoaniline. In one of the reactions studied, a chlorinated azoxy derivative was also isolated, and its structure was elucidated by X-ray analysis.

Crystal structures of benzthiazide [6-chloro-3-[[(phenylmethyl)thio]ethyl]4H-1,2,4-benzthiadiazine-7-sulfonamide-1,1,dioxide] in its anhydrate and monohydrate forms reveal, respectively, a J-like folded as well as extended type conformations that have critical torsional flexibility along the C–C–S–C bonds and novel H-bonded sulfonamide motifs.

2-Phenyl-3H-indol-3-one N-oxide (2-phenylisatogen), 2-phenyl-3-phenylimino-3H-indole N-oxide and 2-phenyl-3H-indole N-oxide (the tautomeric form of 1-hydroxy-2-phenylindole) reacted in refluxing toluene with maleimides with different substituents at the nitrogen, yielding 1,3-cycloaddition products. The cycloaddition was diastereoselective for the first two nitrones, whereas in the case of 2-phenyl-3H-indole N-oxide only the formation of the endo cycloadduct was observed. This different behaviour is attributed to the substituent at C-3 of the five-membered ring in the indole nucleus. In 95% ethanol at room temperature, metal cations such as CoII, CuII, CaII, MnII, ZnII, and NiII catalyse the reaction between 2-phenylisatogen and N-phenylmaleimide without substantially affecting the diastereoselectivity. The crystal structures of endo-3a,10,10a,10b-tetrahydro-10aphenyl-1H-pyrrolo[3′,4′:4,5]isoxazolo[2,3-a]indole-1,3,10trione (5a), endo-2-methyl-10a-phenyl-3a,10,10a,10b-tetrahydropyrrolo[3′,4′:4,5]isoxazolo[2,3-a]indole-1,3-dione (8a), and endo-2,10a-diphenyl-3a,10,10a,10b-tetrahydropyrrolo[3′,4′:4,5]isoxazolo[2,3-a]indole-1,3-dione (8b) are reported.

The synthesis of 1-(2-cyano-2-methoxyiminoacetyl)-3-ethylurea leads to only one of the two possible diastereomers, which has been found to be in the E-configuration by X-ray analysis.

2-Phenyl-3-phenylimino-3H-indole N-oxide (an indolic nitrone) reacts with triethyl and triisopropyl phosphite in refluxing xylene and tert-butylbenzene to give 2-phenyl-3-phenylimino-3H-indole (indolenine) in very good yield. The same reaction carried out in refluxing phosphite gave rise to a series of compounds which in part derive from the thermal rearrangement of the starting nitrone and in part from the interaction of the indolenine with phosphites. The formation of the products arising from the reduction of the indolenine is explained by an electron transfer process between this intermediate and the phosphite; whereas the formation of the phosphorylated products is interpreted through the evolution of the intermediate zwitterion generated by the nucleophilic attack of the phosphite on carbon- 2 of the indolenine. The formation of this intermediate is also discussed in terms of an electron transfer process. Crystal structures of 1-diethylphosphoryl-2-phenyl-3-phenylamino-1H-indole and 2-phenyl-4-phenylimino-4H-3,1-benzoxazine are also described.

Magnetocaloric properties of Mn-rich compounds in the vicinity of the co-occurrence of magnetic and structural transitions were investigated. Polycrystalline samples with nominal compositions ranging from Ni/sub 47.5/Mn/sub 33.5/Ga/sub 20/ to Ni/sub 50/Mn/sub 30/Ga/sub 20/ were prepared by arc melting technique. Sample composition, structure, martensitic and Curie transition temperatures were determined by energy dispersion spectrometry, X-ray diffraction and thermomagnetic analysis.

In this work polycrystalline perovskite with composition La0.7Ca0.3Fe0.05Mn0.95O3 has been produced by standard ceramic method. A considerable change occurs in magnetic, transport and magnetoresistance properties with respect to the classic composition without Fe. The introduction of a different metal, Fe, in Mn-O layer causes a decrease of about 50 K in the value of TC. In the same way, a decrease of about 10–15% in the average magnetic moment measured at 1 T is also observed. On the other hand, the introduction of Fe does not cause any appreciable change in the value of the lattice parameter. This new compound presents 60% of giant magnetoresistance ratio at 200 K. Magnetization vs. temperature measurements in zero field cooling and field cooling show clear differences at applied fields below 80 kA m−1. Such a behavior, also observed in La0.7Ca0.3MnO3 sample, is not recognizable as a simple ferromagnetic one. A qualitative discussion of the effect in the magnetic and transport properties of these compounds, caused by the substitution of some Mn atoms by Fe is given.In this work polycrystalline perovskite with composition La0.7Ca0.3Fe0.05Mn0.95O3 has been produced by standard ceramic method. A considerable change occurs in magnetic, transport and magnetoresistance properties with respect to the classic composition without Fe. The introduction of a different metal, Fe, in Mn-O layer causes a decrease of about 50 K in the value of TC. In the same way, a decrease of about 10–15% in the average magnetic moment measured at 1 T is also observed. On the other hand, the introduction of Fe does not cause any appreciable change in the value of the lattice parameter. This new compound presents 60% of giant magnetoresistance ratio at 200 K. Magnetization vs. temperature measurements in zero field cooling and field cooling show clear differences at applied fields below 80 kA m−1. Such a behavior, also observed in La0.7Ca0.3MnO3 sample, is not recognizable as a simple ferromagnetic one. A qualitative discussion of the effect in the magnetic and transport properties of these compou...

The mononuclear copper(II) complexes, [CuL1](ClO4) (1), and [CuL2](ClO4) (2) with unsymmetrical quadridentate Schiff base ligands derived from the 1:1:1 condensation of 2,4-pentanedione, pyridine-2-carboxaldehyde and 1,2-ethanediamine (HL1) or 1,3-propanediamine (HL2) have been prepared and characterised. Complex 2 undergoes Cu(II)/H+ catalysed rearrangement to [CuL3](ClO4)2 (3) where L3 is a symmetrical tetradentate Schiff base involving 1,3-propanediamine and pyridine-2-carboxaldehyde. Structures of all the three compounds have been verified by single crystal X-ray analysis. The geometry around Cu(II) is square-planar in 1 and 2 whereas that in 3 is distorted octahedral with two axially coordinated perchlorate ions.

The reactions of indole with nitrosobenzene in the presence of acetic, monochloroacetic, monobromoacetic and trichloroacetic acid afford as the main product a deep-green precipitate, which in a preceding study had been erroneously identified as the aminyl radical of a trimer indole. The identity of the minor products was confirmed. This paper deals with the determination of the correct structure of the compounds contained in the precipitate through a study based on chemical reactions, electrochemical measurements and X-ray analysis.

The title reactions are an example of direct introduction of an aryl group into DNA bases.

(R x Y 1-x )Al 3 (BO 3 ) 4 (R = Nd, Gd; x = 1, 0.6, 0.65, 0.7 and 0.75) single crystals have been grown from fluxed melts. The segregation coefficients of neodymium and gadolinium were estimated to be 0.66-0.92 and 0.88-1.03, respectively. This coefficient increases with an increase of R 2 O 3 /Y 2 O 3 ratio in the initial mixture. The (Nd 0.63 Y 0.37 )Al 3 (BO 3 ) 4 structure was refined. The thermal behavior of the above borates was studied in the temperature range of 940-1030°C. Among the decomposition products, the crystalline aluminoborates Al 4 B 2 O 9 , Al 18 B 4 O 33 and rare earth borates RBO 3 were determined.