Showing papers on "Isostructural published in 1986"
TL;DR: In this article, it was shown that chloro and methyl groups can be interchanged in a molecule without altering the crystal structure and that crystal stabilization is mainly through dispersive and repulsive interactions Violations of this rule are observed when directional forces or weak bonds are involved.
Abstract: Since chloro and methyl groups have nearly the same volume, they may be interchanged in a molecule without altering the crystal structure Such isostructural behaviour is found when crystal stabilization is mainly through dispersive and repulsive interactions Violations of this rule are, however, observed when directional forces or weak bonds are involved and the failure of complete chloro-methyl exchange in a substance like hexachlorobenzene, points to the importance of weakly attractive ClCl interactions
75 citations
TL;DR: In the space group Pmnb with a = 6.9041(1), b = 9.0882 (1), and c = 5.1134(1)A as discussed by the authors, the calculated density is 3.580 g/cm 3 (V = 320.84A 3 ).
68 citations
TL;DR: Les deux composes du titre cristallisent dans le systeme monoclinique, groupe d'espace P2 1 /c et leur structure est affinee jusqu'a R=0.038 et R= 0.078 as mentioned in this paper.
48 citations
TL;DR: In this paper, the paramagnetic species [Co 6 (μ 3 -S) 8 (PEt 3 ) 6 ] (Y ) (Y = BPh 4, (1), PF 6, (2 )).
46 citations
TL;DR: In this paper, powder neutron diffraction data have been used to refine the crystal structure of KBaFe2(PO4)3 at 4.2 K. The material is isostructural with the mineral langbeinite, having two crystallographically distinct, octahedrally coordinated Fe3+ ions in the asymmetric unit.
46 citations
TL;DR: In this paper, ternary chalcogenides with TlV5S8 and tlV6S8 were synthesized directly from the elements: InTi5Se7.8, TlCr5Te7.4V6 (Se6.8P1.0).
40 citations
TL;DR: In this paper, the authors studied the Ba2SiO4-Ca2 SiO4 system by heating mixtures of the two components at 1723 K. Six distinct phases resulted; they were examined by both X-ray diffraction and differential thermal analysis.
Abstract: The system Ba2SiO4-Ca2SiO4 was studied by heating mixtures of Ba2SiO4 and Ca2SiO4 at 1723 K. Six distinct phases resulted; they were examined by both X-ray diffraction and differential thermal analysis. The phases β-(Ba0.05Ca1.95)SiO4 and α-(Ba0.15Ca1.85)SiO4 are isostructural with corresponding high-temperature modifications of Ca2SiO4. The X phase (Ba0.48Ca1.52SiO4) is orthorhombic, is a pure phase rather than a solid solution, and is defined for the first time in the present work. The T phase (Ba1.31Ca0.69SiO4) is hexagonal and interpreted in terms of a unit cell with a doubled c parameter, in contrast with literature data.
33 citations
TL;DR: In the isostructural series of β-(BEDT-TTF) 2X organic metals, abbreviated β-(ET)2X, where X is a trihalide anion, I3-, I2Br- or IBr2-, and where ET is bis-(ethylenedithio) tetrathiafulvalene (C10S8H8) as mentioned in this paper, the salt containing the disordered asymmetric I 2Br- anion has atypical structural and electronic properties compared to those containing the symmetrical and ordered I-3 and
Abstract: In the isostructural series of β-(BEDT-TTF)2X organic metals, abbreviated β-(ET)2X, where X is a trihalide anion, I3-, I2Br- or IBr2-, and where ET is bis-(ethylenedithio) tetrathiafulvalene (C10S8H8), the salt containing the disordered asymmetric I2Br- anion has atypical structural and electronic properties compared to those containing the symmetrical and ordered I-3 and IBr2- anions.
31 citations
TL;DR: In this article, a new anion [Co6C(CO)13] has been prepared by refluxing a solution of [Co 6C( CO)15]2 in tetrahydrofuran under nitrogen; the loss of CO causes rearrangement of the metal cluster from trigonal prismatic to octahedral; the reaction is reversible, and on simple exposure to CO the starting anion is regenerated.
Abstract: The new anion [Co6C(CO)13]2– has been prepared by refluxing a solution of [Co6C(CO)15]2– in tetrahydrofuran under nitrogen; the loss of CO causes rearrangement of the metal cluster from trigonal prismatic to octahedral; the reaction is reversible, and on simple exposure to CO the starting anion is regenerated. The new anion has been characterized by single-crystal X-ray diffraction on the salt [NEt4]2[Co6C(CO)13] which crystallizes in the monoclinic space group C2, with cell constants a= 20.750(2), b= 11.470(2), c= 16.097(2)A, β= 91.968(3)°, and Z= 4. The structure has been solved from 6 066 reflections, collected by counter methods and refined by leastsquares calculations to R= 0.0295. The dianion possesses idealized C2 symmetry and contains a distorted octahedron of cobalt atoms, whose cavity is occupied by the carbide atom. Five carbonyl ligands are bridging on opposite edges of the three octahedron equators, and eight are terminal. The dianion is not isostructural with the isoelectronic congener [Rh6C(CO)13]2– thus showing a new way of arranging 13 CO ligands on an octahedral core of metal atoms.
31 citations
TL;DR: In this paper, the newly reported species CpMoIr 3 (CO) 11 has been subjected to an X-ray structural analysis and crystallizes in the centrosymmetric orthorhombic space group Pbca.
30 citations
TL;DR: The results of a comparative theoretical study of the dipole moment derivatives and infrared absorption intensities within the double harmonic approximation are presented for the isoelectronic, isostructural C 2v molecules: H 2 F +, H 2 O and NH − 2.
TL;DR: In this paper, the preparation of bimetallic carbonyl clusters having the general formula [Ni 9 Pt 3 (CO) 21 H - n ] n − (n = 4, 3, 2) is described.
TL;DR: In this paper, the existence of an additional new phase which it is proposed be denoted by η-Ti3N2−x was revealed by quenching Ti-N alloys with about 30 at.% N from 1333-1363 K to room temperature.
Abstract: Phase equilibria studies in the Ti-N system have revealed the existence of an additional new phase which it is proposed be denoted by η-Ti3N2−x. This phase was obtained by quenching Ti-N alloys with about 30 at.% N from 1333–1363 K to room temperature. X-ray powder patterns of η-Ti3N2−x could be indexed on the basis of a rhombohedral unit cell, space group D 5 3d -R 3 m (No. 166), with the rhombohedral unit cell parameters (standard deviations in parentheses): ar = 0.74236(29) nm and α = 23.16(1) °, or, in the hexagonal setting: ah = 0.29809(4) nm and ch = 2.16642(85) nm with c h a h = 7.268(4) . In the hexagonal setting the titanium atoms occupy the sites 6(c) with z = 0.2222 and 3(a) whereas the nitrogen atoms are apparently randomly distributed among the sites 6(c) with z = 0.3889 and 3(b). η-Ti3N2−x is isostructural with ϵ-Hf3N2−x and Ta2VC2−x and contains considerably less nitrogen than Ti3N2.
TL;DR: In this article, the lattice dynamics of isostructural tetrahalozincates were probed down to 70 K in order to cover the successive phase sequences, and the unit cell dynamics was understood in terms of 84 phonon branches originating from various internal modes of tetrahedral ZnX2−4 group and external lattice modes.
TL;DR: In this paper, the properties of the tetrabutylammonium trihalides were investigated and it was shown that the I3−, IBr2−2 and AuI2− anions are essentially linear and symmetrical whereas the I2Br− salt contains linear but non-symmetrical I-I-Br− anion.
TL;DR: In this paper, the first three, title complexes showed that they are isostructural, the M(PPh3) fragment bridging the same Ru-Ru bond as that bridged by the PPh group of the face-capping phosphidophosphine ligand.
Abstract: Reactions between K[BHBus3] and [Ru3(CO)10(µ-EPh2CH2EPh2)](E = P or As) afford solutions of the dephenylated anions, [Ru3(µ3-EPhCH2EPh2)(CO)9]–, which can be reversibly protonated to give [Ru3(µ-H)(µ3-EPhCH2EPh2)(CO)9] The latter complexes may also be obtained directly from [Ru3(CO)10(µ-EPh2CH2EPh2)] and H2(20 atm, 80 °C, 2h) in cyclohexane (yields 65–75%) Similar complexes were obtained in poor yield from [Ru3(CO)10(µ-PPh2CH2CH2PPh2)] The group 1 B metal-containing clusters [MRu3(µ3-EPhCH2EPh2)(CO)9(PPh3)](E = P, M = Cu, Ag, or Au; E = As, M = Au) were prepared from [Ru3(µ3-EPhCH2EPh2)(CO)9]– and sources of [M(PPh3)]+; the analogous [AuRu3(µ3-PPhCH2CH2PPh2)(CO)9(PPh3)] was also obtained Single-crystal X-ray studies on the first three, title complexes showed that they are isostructural, the M(PPh3) fragment bridging the same Ru–Ru bond as that bridged by the PPh group of the face-capping phosphidophosphine ligand Detailed examination of bond parameters in the Ru2MP moiety suggests that the three M(PPh3) fragments are not strictly isolobal, although it is the Ag(PPh3) fragment which interacts least strongly with the Ru3 core The structures were refined by least-squares methods to residuals of 0039, 0044, and 0041 for 4 560, 4 917, and 9 275 independent ‘observed’ reflections, respectively
TL;DR: In this article, ternary intermetallic germanides and plumbides were identified by X-ray powder diffraction and they are isostructural with already known stannides (phases I, II and II′ or III).
TL;DR: In this paper, a model for the magnetic structure of FePO4-II is proposed, which consists of weakly ferromagnetic [001] chains, coupled together antiferromagnetically.
TL;DR: A structural determination was carried out on powdered samples of Li2NbF6 and Na2NfF6, the first two compounds of a new series of hexafluoroniobates IV: M 2 NbF5 with M = alkali metal, NH+4.2 K and room temperature as mentioned in this paper.
TL;DR: The crystal structures of three compounds containing eight-membered Si4(N,O)4 rings have been determined: [t-Bu2SiOSiMe2O]2 (I), [t -BuSiOSIMe2NH]2(II) and [i-Pr2SiNH]4 (III) as mentioned in this paper.
TL;DR: In this article, the crystal structure of 1:1 gadolinium/ytterbium orthophosphate has been determined by means of single crystal X-ray diffraction techniques.
TL;DR: In this paper, a two-phase Rietveld analysis showed that Cs3Cr2I9 exists in two modifications, which are both present in the same sample.
01 Nov 1986
TL;DR: In this paper, the formation of spinelloid phases can be associated with the inverse character of the spinel component in spinel-olivine oxide (SOO) compounds.
Abstract: Spinelloid phases have been observed and characterized by powder X-ray diffraction and high-resolution electron microscopy. Mg3Ga2GeO3(III), with a narrow composition range of approximately 3 mole percent Mg2GeO4, is stable at atmospheric pressure up to about 1,420° C, and is isostructural with β-Mg2SiO4 and the spinelloid Phase III of the NiAl2O4-Ni2SiO4 system. This represents the first occurrence of a β-phase structure stable at 1 atm pressure. Above 1,420° C (1 atm) Mg3Ga2GeO8 (III) decomposes reversibly into a mixture of spinel and olivine. At high pressure (around 30 kbar at 1,100° C) it transforms into another spinelloid phase, Mg3Ga2GeO8 (IV), isostructural with Phase IV of the NiAl2O4-Ni2SiO4 system. In terms of crystal structures and phase relations therefore there exists a close analogy between the magnesium gallo-germanate and nickel alumino-silicate systems, the former being a lower-pressure analogue of the latter. Our investigation of a number of other pseudo-binary spinel-olivine oxide systems suggests that the formation of spinelloid phases can be associated with the inverse character of the spinel component.
TL;DR: In this article, the NMR spectra of tetraalkoxygermanes with different substituents have been studied and it has been shown that the magnitude of (p-d ) τ -bonding in the GeO bond is smaller than in the SiO bond.
TL;DR: In this article, a neptunyl(VI) carbonate was precipitated at pH 5 from a nitrate solution by the addition of solid lithium carbonate, and the precipitate was characterived by thermogravimetric analysis, v-ray diffraction and 237Np Mossbauer measurements.
Abstract: Neptunyl(VI) carbonate was precipitated at pH 5 from a neptunyl(VI) nitrate solution by the addition of solid lithium carbonate. The precipitate was characterived by thermogravimetric analysis, v-ray diffraction and 237Np Mossbauer measurements. NpO2CO3 decomposes at 350–400 °C and was found to be isostructural with UO2CO3. The lattice parameters are a = 4.82(1)A, b = 9.17(5) A and c = 4.24(2) A . The 4.2 K Mossbauer absorption spectrum can be described as a vuadrupole interaction with the hyperfine parameters δ = −35.5(2) mm s−1 (relative to NpAl2), ¦e 2 vv¦= 231(1) mm s−1 and η = 0.21(2). Both isomer shift and electric field gradient values are consistent with a neptunyl NpO2+2 ion and confirm the crystal structure isotypic with UO2CO3.
TL;DR: In this article, the thermal behavior of a family of isostructural ordered bimetallic MM'(EDTA)·6H 2 O complexes has been performed using TG and DTA.
TL;DR: In this paper, the X-ray crystal structures of the metallacyclobutane derivatives have been determined and their crystal structures, refined to R= 0.0441 and O(0.0389 for (2) and (6) respectively, are built up of deformed "three-legged piano stools", one leg being the M-P bond.
Abstract: The interaction of [RhCl2(η5-C5Me5)(PPh3)] with Mg(CH2CMe3)Cl in pentane gives the rhodacyclo butane [[graphic omitted]H2)(η5-C5Me5)(PPh3)](2). The analogous reaction of [MCl2(η5-C5Me5)(PPh3)](M = Rh or Ir) with Mg(CH2SiMe3)Cl allows the isolation of the dialkyl derivatives [M(CH2SiMe3)2(η5-C5Me5)(PPh3)]. Thermolysis of [Ir(CH2SiMe3)2(η5-C5Me5)(PPh3)] in cyclohexane leads to the iridasilacyclobutane derivative [[graphic omitted]H2)(η5-C5Me5)(PPh3)](6). The mechanism of formation of the metallacyclobutane derivatives is discussed. The X-ray crystal structures of (2) and (6) have been determined. The two metallacycle compounds give isostructural crystals belonging to the P21/n space group with four molecules in the unit cell of dimensions for (2): a= 17.199(6), b= 10.987(4), c= 16.064(5)A,β= 109.54(2)°; (6): a= 17.098(7), b= 11.294(5), c= 15.977(7)A,β= 108.17(2)°. Their crystal structures, refined to R= 0.0441 and 0.0389 for (2) and (6) respectively, are built up of deformed ‘three-legged piano stools’, one leg being the M–P bond [Rh–P = 2.230(2), Ir–P = 2.236(2)A], the other two being the M–C a bonds [Rh–C = 2.1 00(5)(av.), Ir–C = 2.1 59(7)A(av.)] of the metallacyclobutane ring with C–Rh–C = 66.8(2) and C–Ir–C = 77.3(4)°. These rings are puckered: angle between M–C ⋯ C and E–C ⋯ C = 16.5(4) and 18.9(6)° for (2)(E = C) and (6)(E = Si), respectively.
TL;DR: In this article, the standard molar entropy of tetraphenylarsonium tetrahenylborate was determined from calorimetric data where available and statistically from published spectroscopic and structural data.
Abstract: Tetraphenylarsonium tetraphenylborate, widely used as a reference electrolyte, is often related to neutral compounds isostructural with its constituent ions. Thermodynamic information concerning them is lacking. Standard molar entropies of the gaseous ions Ph4B–, Ph4P+, and Ph4As+, the species Ph4C, Ph4Si, Ph4Ge, Ph4Sn and Ph4Pb, and the related compounds Ph3CH and Ph2CH2 have been determined from calorimetric data where available and statistically from published spectroscopic and structural data. The latter calculation, deemed more reliable by us, gave the values (in J K–1mol–1): 654, 649 and 648 for the ions, 639, 661, 664, 680 and 694 for the neutral Ph4M compounds, and 541 and 436 for the tri-and di-phenylmethanes. The standard partial molar entropy of the Ph4B– anion is 348 J K–1mol–1, hence its entropy of hydration is —306 J K–1mol–1. This value and the presumed similar one for Ph4As+ indicate that these ions enhance the structure of water. The standard partial molar heat capacities of aqueous Ph4P+, Ph4As+ and Ph4B– are 1231, 1258 and 1051 J K–1mol–1, and those of the gaseous ions are 370, 372 and 367 J K–1mol–1, respectively. The heat-capacity changes on hydration also indicate these ions to be water-structure-makers.
TL;DR: In this paper, the crystal structure of a novel organic conductor δ-(BEDT-TTF) 2AuBr2 (BEDTs TTF: bis(ethylenedithio)tetrathiafulvalene) is determined by X-ray analysis.
Abstract: The crystal structure of a novel organic conductor δ-(BEDT-TTF) 2AuBr2 (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene) is determined by X-ray analysis. This salt is essentially isostructural with δ-(BEDT-TTF)2AuI2 and one-dimensional along the adjacent stacks. Along this direction a two-fold superlattice is present at room temperature. The resistivity and the thermoelectric power exhibit anomalies above 320 K.