1,721,186 research outputs found
Demicheleite-(Cl), BiSCl, a new mineral from La Fossa crater, Vulcano, Aeolian Islands, Italy.
No full textDemicheleite-(Cl), ideally BiSCl, is the chlorine analog of demicheleite-(Br) and is closely related to this species that occurs in the same locality. The mineral is the first natural bismuth sulfochloride discovered so far in a natural environment, and it is identical with the corresponding and already known synthetic compound. It was found in an active medium-temperature intracrater fumarole at La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy. The mineral occurs as acicular to stout translucent crystals up to 0.25 mm long in an altered pyroclastic breccia, together with demicheleite-(Br), bismoclite, bismuthinite, godovikovite, panichiite, and three new minerals pending the IMA approval (IMA 2008-015, IMA 2008-039, and IMA 2008-057). The mineral is orthorhombic, space group Pnam, with a = 7.7933(10), b = 9.9293(12), and c = 3.9880(4) Å, V = 308.60(4) Å3 (from X-ray powder data), Z = 4. The crystal habit is prismatic with {110} as the dominant form, terminated by minor faces of another prism {011}, a pinacoid {010}, and a bipyramid {111}. The color is dark red to black; the luster submetallic. It is non-fluorescent. The tenacity is brittle. The cleavage and fracture were not observed. The calculated density is 5.934 g/cm3.
The chemical analysis obtained by WDS electron microprobe gave (wt%) Bi 72.74, Cl 11.42, Br 3.13, S 11.74, Se 0.01 wt%, total 99.04, corresponding to the empirical formula (based on 3 apfu): Bi0.97(Cl0.90Br0.11)Σ1.01S1.02.
The crystal structure has been refined to a final R index of 0.0218 and contains Bi in sevenfold coordination inside a monocapped trigonal prism. By base sharing, these polyhedra form rows extending
along [001]. The rows are connected with symmetry-related rows by sharing S-S edges of the pyramidal caps; these pairs of rows are linked to the others by sharing Cl/Br atoms. The distribution of bond lengths is close to that of the synthetic counterparts BiSCl and BiSBr, with Bi-S distances of 2.601(2) and 2.709(1) Å, and Bi-Cl/Br distances of 2.937(1) and 3.388(1) Å.
The strongest 6 lines in the X-ray powder diffraction pattern [dobs(Å) (I) (hkl)] are: 2.896 (100) (121), 4.174 (45) (120), 2.684 (42) (211), 2.784 (33) (201), 1.725 (30) (411), 2.543 (27) (031).
Both the mineral and the mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification of the IMA (no. 2008-020)
MECHANISTIC STUDY OF THE CARBONYLATION OF NITROBENZENE CATALYZED BY THE [RH(CO)4]- NITROGEN BASE SYSTEM - X-RAY STRUCTURE OF [PPN][RH(CO)2ON(C6H3CL2)C(O)O]
No full text[PPN] [Rh(CO)4] (1) reacts with ArNO2 or ArNO to yield the same product (Ar = Ph, 2; Ar = 3,4-Cl2-C6H3, 3). The reaction of 1 with nitrosoarenes also produces the corresponding azoxyarenes. The product was structurally characterized in the case of Ar = 3,4-dichlorophenyl and was shown to be [PPN][Rh(CO)2ON(C6H3Cl2)C(O)O] (3). Crystal data for 3: C45H33Cl2N2O5P2Rh.C4H8O, M(r) = 989.64, triclinic, space group P1BAR (No. 2), a = 10.798(4) angstrom, b = 9.889(6) angstrom, c = 21.648(6) angstrom, a = 89.77(1)degrees, beta = 96.00(1)degrees, gamma = 92.71(1)degrees, V = 2296(2) angstrom2, Z = 2, D()c = 1.431 g cm-3, Mo Kalpha radiation (lambda = 0.710 73 angstrom), mu(Mo Kalpha) = 6.00 cm-1, R = 0.037 (R(w) = 0.047) for 5299 independent reflections having I > 3sigma(I). Both of the reactions proceed through electron transfer to the nitroso or nitro derivative. Reaction of 2 and 3 with MeOH and CO produced the corresponding amine or the methyl carbamate, depending on the experimental conditions. The reaction of 3 with MeOH/CO was faster in the presence of nitrogen bases, and aniline was shown to be an intermediate in the synthesis of the carbamate. When the same reaction was performed in the presence of a large excess of nitrosobenzene, the two isomeric mixed azoxybenzenes 3,4-Cl2-C6H3N(O)=NPh and 3,4-Cl2-C6H3N=N(O)Ph were the largely dominant products, which strongly suggests the intermediate formation of a nitrene complex
SYNTHESIS AND CRYSTAL-STRUCTURE OF [PPH4]2[IR4(CO)10(CH2COOME)2] AND [PPH4][IR4(CO)11(CH2COOME)] - 1ST EXAMPLES OF IRIDIUM CLUSTERS BEARING AN ALKYL-LIKE LIGAND
No full textThe reaction of Na[Ir(CO)4] ([Na]1) with given amounts of BrCH2COOMe in THF, followed by treatment with PPh4Cl, gave high yields of the two novel clusters [PPh4]2[Ir4(CO)10(CH2COOMe)2] ([PPh4](2)2) and [PPh4] [Ir4(CO)11(CH2COOMe)] ([PPh4]3). The reaction takes place in two steps; the first compound formed is 2, which then reacts, in a slower reaction, with excess BrCH2COOMe to afford 3. To the best of our knowledge, 2 and 3 are among the first examples of clusters bearing an alkyl or alkyl-like substituent. X-ray diffraction analysis of the clusters was carried out on crystals obtained by using PPh4+ as a countercation. Compound [PPh4](2)2 is triclinic, space group P1BAR, with a = 11.163 (2) angstrom, b = 12.807 (2) angstrom, c = 22.849 (3) angstrom, alpha = 84.76 (1)-degrees, beta = 88.76 (1)-degrees, gamma = 73.53 (1)-degrees, Z = 2, R = 0.034, and R(w) = 0.042 for 6373 independent reflections with I > 3-sigma(I). Compound [PPh4]3 is monoclinic, space group P2(1)/c, with a = 13.155 (4) angstrom, b = 24.593 (5) angstrom, c = 38.401 (8) angstrom, beta = 91.00 (3)-degrees, Z = 12, R = 0.065, and R(w) = 0.069 for 5227 independent reflections with I > 3-sigma(I). Both anions contain a tetrahedron of iridium atoms with three bridging CO ligands around a triangular basal face of the metal tetrahedron, the alkyl-like substituents being axially bonded to the iridium atoms of this face. The reactivity of the sodium salt of [Ir(CO)4]- with BrCH2COOMe was quite different from that, already reported by us, of the same anion with PPN+ (PPN+ = (PPh3)2N+) as a countercation. This latter reaction forms only mononuclear species. The possible role of Na+ in the formation of the clusters is discussed
Use of amido Grignard reagents in inorganic chemistry : Synthesis and crystal structure of anti-[Pd(Cl)(py)(mu-2,6-Pri2C6H3NH)](2)
Full text linkTreating a pyridine (py) solution of PdCl2(py)(2) with a tetrahydrofuran or diethyl ether solution of the amido Grignard reagent 2,6-(Pr2C6H3NH)-C-1(MgCl) afforded a dimeric palladium complex, containing two bridging amido groups, which has been structurally characterised
PANICHIITE, NATURAL AMMONIUM HEXACHLOROSTANNATE(IV), (NH4)2SnCl6, FROM LA FOSSA CRATER, VULCANO, AEOLIAN ISLANDS, ITALY
No full textPanichiite, ammonium hexachlorostannate(IV), (NH4)2SnCl6, is a new mineral species found in a medium-temperature
intracrater fumarole (~250°C) at La Fossa crater, Vulcano Island, Aeolian Islands, Sicily, Italy. The mineral occurs as aggregates
of minute colorless octahedra up to 0.2 mm in diameter on fragments of altered pyroclastic breccia, in association with
alunite, anhydrite, bismuthinite, godovikovite, demicheleite-(Br) (BiSBr), BiSCl (IMA 2008–020) and two other new species,
a sodium ammonium aluminum sulfate chloride (IMA 2008–057) and an ammonium bismuth chloride that is presently under
study. Panichiite is cubic, space group Fm3m (no. 225), with Z = 4; the unit-cell parameter a is 10.064(1) Å, and V is equal to
1019.4(2) Å3. The X-ray powder-diffraction pattern is in excellent agreement with that of the synthetic compound; the strongest
six reflections [dobs in Å(I)(hkl)] are: 5.811(100)(111), 5.032(73)(200), 2.516(69)(400), 3.035(48)(311), 1.779(42)(440), and
2.250(39)(420). Chemical analyses obtained with an electron microprobe in energy-dispersion mode gave, on average, Cl 56.57,
Sn 31.62, Br 1.53, K 1.05, total 90.77, with NH4+ (by difference) 9.23, for a total of 100.00 wt.%, corresponding to the empirical
formula [(NH4)1.90K0.10]S2.00Sn0.99(Cl5.94Br0.07)S6.01. The calculated density for the compound with the above empirical formula
is 2.423 g/cm3. The index of refraction n obtained using immersion methods is 1.68(1) (l = 589 nm). The structure, including the
positions of the hydrogen atoms of the ammonium ion, was refined from single-crystal diffraction data to a final R of 0.030 for
153 independent observed reflections [I > 2s(I)]. The six equivalent Sn–Cl distances in the octahedral SnCl62– ion are 2.429(1)
Å, and the Cl...N distances are 3.559(1) Å. The mineral (IMA 2008–005) is named in honor of Prof. Ugo Panichi, a pioneer in
the study of minerals from Vulcano
Aluminopyracmonite, (NH4)3Al(SO4)3, a new ammonium aluminium sulfate from La Fossa crater, Vulcano, Aeolian Islands, Italy
No full textThe new mineral aluminopyracmonite, ideally (NH4)3Al(SO4)3, was found in a medium-temperature (~250oC) intracrater active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. It occurs on a pyroclastic breccia as colourless to white prismatic crystals up to 0.2 mm long, in
association with adranosite, mascagnite, alunite and salammoniac. The mineral is identical to the
synthetic compound (NH4)3Al(SO4)3. It is trigonal, space group: R-3 (no. 148) with a = 15.0324(8), c = 8.8776(5) A, V = 1737.3(2) A^3 and Z = 6. The six strongest reflections in the X-ray powder diffraction pattern are: [dobs in A (I)(hkl)] 3.336(100)(131), 7.469(62)(1 1 0), 3.288(60)(122), 4.289(45)(-231), 2.824(29)(-351), 4.187(27)(012). The empirical formula based on 12 anions is [(NH4)2.89K0.10]S2.99(Al1.18Fe0.01)S1.19S2.91O12, and the simplified formula (NH4,K)3Al(SO4)3. The
measured density is 2.12(1) g/cm3, calculated density 2.143 g/cm3. The mineral is uniaxial(–) with omega =
1.545(3) and epsilon = 1.532(3) (lambda = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R(F) = 0.0258 for 998 independent observed reflections [I > 2s(I)]. In spite of having unitcell
parameters comparable with those of pyracmonite, the two minerals are not isostructural; the difference is related to a disordered conformation of the sulfate anions about the two independent Al3+ ions in aluminopyracmonite
F. Cristiani, F. Demartin, F. A. Devillanova, F. Isaia, V. Lippolis, G. Verani Spectroscopic studies of charge-transfer complexes of 1,4,7-trithiacyclononane with diiodine.
No full text1,4,7-Trithiacyclononane ([9]aneS3) reacts with molecular diiodine in CH2Cl2 to form a 1:1 adduct. The formation constant and the thermodynamic parameters of this adduct have been determined by UV-visible spectra of several solutions at the temperatures of 15, 20, 25, 30, and 35-degrees-C. The C-13 NMR spectra show that adducts with higher ligand/diiodine molar ratios are formed. Two neutral charge-transfer molecular compounds having formula 2[9]aneS3 . 4I2 (I) and [9]aneS3 . 3I2 . (II) have been obtained as crystals. The crystals of I are triclinic (a = 8.498(2) angstrom, b = 13.984(4) angstrom, c = 14.898(6) angstrom, alpha = 65.57(2)degrees, beta = 89.19(2)degrees, gamma = 81.26(2)degrees, Z = 2, space group P1BAR; R = 0.025) and contain units formed by two [9]aneS3 molecules connected by a diiodine molecule; one [9]aneS3 binds two other diiodine molecules, while the second binds only one other diiodine molecule. The crystals of II are monoclinic (a = 13.810(2) angstrom, b = 9.829(4) angstrom, c = 16.198(6) angstrom, beta = 113.41(2)degrees, Z = 4, space group P2(1)/c; R = 0.019) and contain molecules of [9]aneS3 binding three diiodine molecules. FT-Raman spectra in the characteristic nu(I-I) region, carried out on the solid adducts, are discussed in comparison with the structural parameters
BRONTESITE, (NH4)3PbCl5, A NEW PRODUCT OF FUMAROLIC ACTIVITY FROM LA FOSSA CRATER, VULCANO, AEOLIAN ISLANDS, ITALY
No full textThe new mineral species brontesite, ammonium lead chloride (NH4)3PbCl5, was found in a medium-temperature (~250°C) active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. The mineral occurs on a pyroclastic breccia as colorless to white tabular crystals up to 0.1 mm in length, in association with bismuthinite, godovikovite, demicheleite-(Cl), demicheleite-(Br), alunite, IMA 2008–057, (NH4)4NaAl2(SO4)4Cl(OH)2, and IMA 2009–049, BiSI. The mineral is orthorhombic, space group Pnma (no. 62), with Z = 4; the unit-cell parameters are: a 8.434(1), b 15.759(2), c 8.462(1) Å, V 1124.7(2) Å3. The strongest six reflections in the X-ray powder-diffraction pattern [dobs in Å(I)(hkl)] are: 3.067(100)(132), 2.020(80)(342), 2.710(78)(241), 1.910(78)(134), 2.421(75)(152) and 1.491(75)(373). Chemical analyses made with an electron microprobe in EDS mode gave, on average, Pb 47.8, Cl 36.1, Br 3.7, K 1.1, NH4 11.3 (by difference), for a total of 100.0 wt.%, corresponding to the empirical formula: [(NH4)2.87K0.13]S3.00Pb1.09(Cl4.79Br0.21)S5.00. The measured density is 2.72(1) g/cm3. The average index of refraction n is 1.70(3) (l = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R = 0.0238 for 1463 independent observed reflections [I > 2s(I)]. The coordination polyhedron of the independent eight-coordinated Pb atom is a bicapped trigonal prism with Pb–Cl distances ranging from 2.777(1) to 3.724(1) Å. The Pb polyhedra are connected by sharing edges to form chains running along [100]. There are also two independent sites occupied by ammonium ions whose environment corresponds nearly exactly to that of the Rb atoms in Rb3PbCl5. It is essentially similar to that of the lead atom, i.e., the chlorine atoms are also arranged at the corners of bicapped trigonal prisms. There is some substitutional disorder involving the Pb2+ and NH4+ ions, similar to that occurring for Pb2+ and K+ in the high-temperature modification of KPb2Cl5. The mineral was approved as a new species by the IMA Commission on New Minerals, Nomenclature and Classification (IMA #2008–014); it is named after Brontes (Brnth), one of the three Cyclops (Knklvp) and a son of Uranus
Deoxygenation reaction of 2-nitrophenol. Synthesis and x-ray crystal structure of Ru(OC6H4NO-o)(CO)(PPh3)2
No full textBy reaction of [Ru(CO)3(PPh3)2] with 2-nitrophenol, the deep brown ruthenium(II) complex, [Ru(OC6H 4NO-o)(OC6H4NO2-o)(CO)(PPh 3)2], has been obtained. X-Ray crystallography has shown that the complex contains a o-nitrosophenolate ligand, which co-ordinates to ruthenium in a chelating fashion through its nitroso-nitrogen and phenolic oxygen atoms
Therasiaite, (NH4)3KNa2Fe2+Fe3+(SO4)3Cl5, a new sulfate chloride from La Fossa Crater, Vulcano, Aeolian islands, Italy
No full textThe new mineral therasiaite, ideally (NH4)3KNa2Fe2+Fe3+(SO4)3Cl5, was found in a mediumtemperature
(~250oC) intracrater active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily,
Italy. It occurs on a pyroclastic breccia as brown to dark brown equant to short prismatic crystals up to
0.1 mm in length, in association with salammoniac, kremersite and adranosite. The mineral is
monoclinic, space group: Cc (no. 9) with a = 18.284(4), b = 12.073(2), c = 9.535(2) A ̊ , b = 108.10(3)o,
V = 2000.6(7) A ̊ 3 and Z = 4. The six strongest reflections in the X-ray powder diffraction pattern are:
[dobs in A ̊ (I)(h k l)] 2.812(100)(2 ̄ 2 3), 2.664(77)(5 ̄ 1 3), 3.297(28)(3 3 1 ̄ ), 3.208(14)(5 ̄ 1 ̄2), 3.008(12)(0
4 0), 2.942(11)(3 3 1). The empirical formula (based on 17 anions per formula unit (p.f.u.)) is
(NH4)2.68K1.32Na2.04Fe1.76Al0.12Mn0.12S2.98O11.95Cl5.05. The measured density is 2.41(1) g cm 3, dcalc
= 2.395 g cm 3. The mineral is biaxial ( ) with a= 1.585(3) b = 1.615(3) and g = 1.630(3) (white
light). Using single-crystal diffraction data, the structure was refined to a final R(F) = 0.0240 for 5574
independent observed reflections [I > 2s(I)]. The structure of therasiaite displays a novel topology and
contains two independent, distorted octahedral Fe sites, with the Fe atoms in oxidation state 3+ and 2+,
respectively, each surrounded by three Cl atoms and three oxygens of the sulfate ions. The Fe
octahedra and the three independent sulfate anions are connected to form chains running along [001].
Voids between the chains are occupied by three independent ammonium ions (partially replaced by
K+), one K+ and two Na+ ions. The formula resulting from the structure refinement is
[(NH4)2.25K0.75]KNa2Fe2(SO4)3Cl5
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