Search

Aluminotaipingite-(CeCa), (Ce6Ca3)Al(SiO4)3[SiO3(OH)]4F3 , is a new member of the cerite-supergroup minerals, whose general chemical formula is A 9 XM [ T O3Ø]7 Z 3, (A = REE, Ca, Sr, Na and □; X = □, Ca, Na and Fe2+; M = Mg, Fe2+, Fe3+, Al and Mn; T = Si and P; Ø = O and OH; Z = □, OH and F). It was found in cavities of a leucogranitic orthogneiss at the Casette quarry, Montoso, Bagnolo Piemonte, Cuneo Province, Piedmont, Italy. Crystals of aluminotaipingite-(CeCa) are light pink to pink, transparent or semi-transparent, with a vitreous lustre. It forms pyramidal crystals up to 0.07 mm in size and observed forms are {0 0 1}, {1 0 $\bar{2}$ }. The tenacity is brittle, no distinct cleavage is observed and the fracture is uneven. The mineral does not fluoresce in long- or short-wave ultraviolet light. The streak is white. Hardness (Mohs) = 5. The calculated density is 4.476 g cm–3. The mineral is trigonal, space group R 3 c , with a = 10.658(3), c = 37.865(9) Å, V = 3725(2) Å3 and Z = 6. The eight strongest powder X-ray diffraction lines are [ d obs, Å (I, %) (h k l)]: 8.38(29)(0 1 2), 4.499(28)(2 0 2), 3.282(41)(2 1 4), 2.936(100)(0 2 10), 2.816(51)(1 2 8), 2.669(37)(2 2 0), 2.207 (29)(3 0 12) and 1.935(35)(2 3 8). The structure was refined to R =0.0306 for 2297 reflections with I >2σ(I). The crystal structure of aluminotaipingite-(CeCa) contains two nine-fold coordinated sites (A 1 and A 2), which are occupied mainly by lanthanides, and a third nine-fold coordinated A 3 site containing almost equal amounts of lanthanides and Ca. The X site is vacant and at the octahedral M site aluminium prevails over Fe3+. Among the three independent T sites, T 2 belongs to a (SiO4)4– anion, whereas T 1 and T 3 belong to (SiO3OH)3– anions. Fluorine is involved in coordination with the A 1 and A 3 sites. [ABSTRACT FROM AUTHOR]

The oxidation of thioamide methimazole (C4H6N2S) with molecular diiodine in water afforded the ionic compound [2(C4H5N2S–SN2C4H6)]I3I5 (1) in 1-triclinic and 1-monoclinic polymorphs. The polymorphic nature of [C4H5N2S–SN2C4H6]2I3I5 has been highlighted by comparing the structure of the 1-triclinic form with that of the 1-monoclinic form reported in the literature. No significant geometric differences are observed for the cations in the two polymorphs. The polymorphism is essentially due to a different arrangement in the polyiodide network of the [I5]− and [I3]− components. The FT-Raman spectrum of 1-triclinic shows the characteristic bands in the range 200–50 cm−1 which are in good agreement with the structural features of the polyiodide network. The molecular electrostatic potential maps of the cation methimazole-disulfide [C4H5N2S–SN2C4H6]+ and the bis-cation methimazole-disulfide {[C4H5N2S–SN2C4H6]+}2 in 1-triclinic have been studied to clearly identify the electrostatic potential energy distributions over the cations, and the electron belt and σ-hole areas responsible for the directionality of the non-covalent interactions in the polyiodides. It is suggested that the cation methimazole-disulfide may be a reaction intermediate in the inhibition of thyroid hormones by methimazole. [ABSTRACT FROM AUTHOR]

The tetranuclear iron(III) compounds [Fe4(μ3-O)2(μ-LZ)4] (1–3) were obtained by reaction of FeCl3 with the shortened salen-type N2O2 tetradentate Schiff bases N,N'-bis(salicylidene)-o-Z-phenylmethanediamine H2LZ (Z = NO2, Cl and OMe, respectively), where the one-carbon bridge between the two iminic nitrogen donor atoms guide preferentially to the formation of oligonuclear species, and the ortho position of the substituent Z on the central phenyl ring selectively drives towards Fe4 bis-oxido clusters. All compounds show a flat almost-symmetric butterfly-like conformation of the {Fe4(μ3-O)2} core, surrounded by the four Schiff base ligands, as depicted by both the X-ray molecular structures of 1 and 2 and the optimized geometries of all derivatives as obtained by UM06/6-311G(d) DFT calculations. The strength of the antiferromagnetic exchange coupling constants between the iron(III) ions varies among the three derivatives, despite their magnetic cores remain structurally almost unvaried, as well as the coordination of the metal ions, with a distorted octahedral environment for the two-body iron ions, Feb, and a pentacoordination with trigonal bipyramidal geometry for the two-wing iron ions, Few. The different magnetic behavior within the series of examined compounds may be ascribed to the influence of the electronic features of Z on the electron density distribution (EDD) of the central {Fe4(μ3-O)2} core, substantiated by a Quantum Theory of Atoms In Molecules (QTAIM) topological analysis of the EDD, as obtained by UM06 calculations 1–3. [ABSTRACT FROM AUTHOR]

Aiolosite, ideally [Na.sub.4]Bi[(S[O.sub.4]).sub.3]Cl, or better [Na.sub.2]([Na.sub.2]Bi)[(S[O.sub.4]).sub.3]Cl, is a new sulfate mineral isotypic to apatite. It was found in an active medium-temperature intracrater fumarole at La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy. It occurs as acicular to slender prismatic crystals up to 0.5 mm long in an altered pyroclastic breccia, together with alunite, anhydrite, demicheleite-(Br), demicheleite-(Cl), bismuthinite, and panichiite. The symmetry is hexagonal (class 6/m), space group [P6.sub.3]/m, with a = 9.626(3), c = 6.880(3) [Angstrom], V = 552.1(3) [[Angstrom].sup.3], Z = 2. The habit is prismatic, terminated by the pinacoid or, more rarely, by a bipyramid. Aiolosite is colorless to white, with white streak; the luster vitreous. It is non-fluorescent. The calculated density is 3.589 g/[cm.sup.3]. The mineral is nonpleochroic, uniaxial (+), [n.sub.[omega]], = 1.59(1), [n.sub.[epsilon]] = 1.60(1), mean [n.sub.obs] = 1.593 (589 nm), [n.sub.calc] = 1.620. The chemical analysis gave [Na.sub.2]O 20.65, [K.sub.2]O 0.96, [Bi.sub.2][O.sub.3] 32.49, S[O.sub.3] 41.27, C1 4.02, Br 0.75, ([H.sub.2]O 0.57 from structure refinement), -O = (Cl + Br) 0.98 wt%, total 99.73, corresponding to the empirical formula calculated on the basis of 13 anions: [Na.sub.2][([Na.sub.1.95][K.sub.0.12][Bi.sup.3+.sub.0.83]).sub.[SIGMA] 2.90][S.sub.3.06][O.sub.12.08][[[Cl.sub.0.67][Br. sub.0.06][([H.sub.2]O).sub.0.19]].sub.[SIGMA]0.92]. The crystal structure has been refined to a final R index of 0.048. One of the two independent Ca sites of apatite is exclusively occupied by Na, and the other one by statistically distributed Na and Bi. The [SO.sup.2-.sub.4] anion replaces the P[O.sup.3-.sub.4] anion of apatite; the chloride anion is located in the partially occupied (s.o.f. = 0.81 ) position at x = 0, y = 0, z = 0. Whenever the chloride position is vacant, the position at x = 0, y = 0, z = 1/4 is occupied by water (s.o.f. = 0.19). The strongest 6 lines in the X-ray powder diffraction pattern [[d.sub.obs] ([Angstrom]) (I) hkl] are: 2.853 (100) (121), 2.775 (85) (112), 3.432 (45) (002), 1.965 (35) (222), 2.306 (25) (310), 4.787 (20) (110). Both the mineral and the mineral name have been approved by the IMA CNMNC (No. 2008-015). Keywords: Aiolosite, apatite structure, new mineral species, bismuth, sulfates, crystal structure, Vulcano Island, Aeolian Islands, Italy DOI: 10.2138/am.2010.3337

Demicheleite-(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) [Angstrom], V = 308.60(4) [[Angstrom].sup.3] (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/[cm.sup.3]. 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): [Bi.sub.0.97][([Cl.sub.0.90][Br.sub.0.11]).sub.[SIGMA]1.01][S.sub.1.02]. 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 BiSC1 and BiSBr, with Bi-S distances of 2.601(2) and 2.709(1) [Angstrom], and Bi-Cl/Br distances of 2.937(1) and 3.388(1) [Angstrom]. The strongest 6 lines in the X-ray powder diffraction pattern [[d.sub.obs]([Angstrom]) (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). Keywords: Demicheleite-(Cl), demicheleite-(Br), new mineral species, bismuth, sulfochlorides, crystal structure, Vulcano Island, Aeolian Islands, Italy

Demicheleite, ideally BiSBr, is the first natural bismuth sulfohalogenide so far discovered. It is identical with the corresponding and analogous synthetic compound and is one of the very few minerals where bromine is an essential component. It was found in an active high-temperature fumarole at the rim of La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy. The mineral occurs as prismatic translucent crystals up to 0.5 mm in size in an altered pyroclastic breccia, together with pseudocotunnite, bismoclite, bismuthinite, cotunnite, and challacolloite. The mineral is orthorhombic, space group Priam, with a = 8.0424(9), b = 9.8511(11), and c = 4.0328(5) [Angstrom], V = 319.50(6) [[Angstrom].sub.3], Z = 4 (from single crystal); the habit is prismatic with {110} and {210} as prevailing forms, terminated by minor faces of another prism {011}, a pinacoid {010}, and a bipyramid {111}. The color is dark red to black; the streak is red; the luster submetallic. Non-fluorescent. Tenacity: brittle. Cleavage and fracture: not observed. The calculated density is 6.312 g/[cm.sup.3]. The chemical analysis obtained by EDS microprobe gave (wt%) Bi 67.6(4), Br 17.4(7), Cl 4.1(4), I 0.6(1), S 10.1(1), total 99.8, corresponding to the empirical formula (based on 3 apfu): [Bi.sub.0.99][S.sub.0.97][([Br.sub.0.67] [Cl.sub.0.35][I.sub.0.02]).sub.[SIGMA]=l.04] The crystal structure has been refined to a final R index of 0.037 and contains Bi in sevenfold coordination at the center of a monocapped trigonal prism. By sharing the triangular bases, such polyhedra form rows extending along [001]. These rows are connected to symmetry-related rows by sharing S-S edges of the pyramidal caps; these double rows are connected to each other by sharing Br/Cl atoms. The bond lengths are close to those of the synthetic counterparts BiSBr and BiSCl, with Bi-S bonds 2.593(3) and 2.720(2) [Angstrom] long and Bi-Br/Cl bonds 3.009(1) and 3.488(2) [Armstrong] long. The strongest 6 lines in the X-ray powder diffraction pattern [[d.sub.obs](Angstrom]) (I) hkl] are: 4.220 (68) (120), 3.740 (62) (210), 2.909 (100) (121), 2.036 (47) (321), 1.865 (63) (022), and 1.774 (88) (411). The mineral is named after Vincenzo de Michele (b. 1936), former curator of the Section of Mineralogy of the Museo di Storia Naturale, Milano, Italy. Both the mineral and the mineral name have been approved by the IMA Commission on New Minerals, Nomenclature and Classification (IMA 2007-022). The type specimen is deposited (no. 2007-1) in the Reference Collection of Dipartimento di Chimica Strutturale e Stereochimica Inorganica of Universita degli Studi di Milano. Keywords: Demicheleite, new mineral species, bismuth, sulfobromides, crystal structure, Vulcano Island, Aeolian Islands, Italy

Copper(II) complexes of salen analogues in which the two salicylaldehyde moieties carry different substituents in position 5, producing a push-pull charge asymmetry are presented. The results obtained from the first principles calculations have provided a reliable description of both structural and excited-state properties of the complexes, as well as of their nonlinear optical (NLO) properties.

The new poly(I2) adduct [(Me2ImS)2·(I2)5] (Me2ImS = 1,3-dimethylimidazole-2-thione) has been synthesized and characterized by single crystal X-ray diffraction analysis. Units of [(Me2ImS)2·(I2)5] are located about a crystallographic inversion center, in which five diiodine molecules display interatomic contacts in a "head-to-tail" sequence giving a –(I2)5– chain interacting at each end with one Me2ImS molecule, CCDC 2133501. The S-bonding of Me2ImS to I2 is described as a donor–acceptor interaction in which I2 acts as an acceptor through the σ*(I–I) orbital resulting in an electronic charge transfer from the thioamide moiety. The bond distances d(S–I(1)) (2.504(2) Å) and d(I(1)–I(2)) (3.133(1) Å) are indicative of a strong interaction. Based on the S–I and I–I bond distances, the calculated values of the electronic charge densities, and the Raman spectral data, it is reasonable to represent the compound as an extended polarised system: [(Me2ImS)–I(1)]δ+⋯I(2)δ−⋯I(3)–I(4)δ−⋯(I(5)–I(5)a)⋯Iδ−–I⋯Iδ−⋯[I-(Me2ImS)]δ+. The molecular electrostatic potential maps of the three adducts Me2ImS·I2, Me2ImS·I2·I2, and MeImHS·I2 (MeImHS = methimazole) have been reported to clearly identify the areas of charge increment (electron belt) and depletion (σ-hole), and thus the directionality of the noncovalent interactions. [ABSTRACT FROM AUTHOR]

Research has been conducted on the macrocycles which incorporate N (sub)2 S (sub)3 -, N (sub)2 S (sub)2 O- and N (sub)2 S (sub)2 -donor sets. The interactions of these macrocycles with Pb (super)II, Cd (super)II, and Hg (super)II heavy metal ions in acetonitrile solution have been investigated and the results are reported.

The syntheses of the first examples of selenoparabanic acid derivatives (dialkylimidazolidine-2-selone-4,5-dione, [3e.sup.R], R = Me, Et, Bu) are presented along with the X-ray crystal structure determination of 3[e.sup.Et]. To gain an insight in the properties of parabanic acid derivatives on the basis of their electronic structures, we report the results of comparative hybrid-DFT calculations performed on parabanic, thioparabanic, and selenoparabanic acids ([3a.sup.H], [3b.sup.H], and [3e.sup.H] and on their N,N'-dimethyl derivatives [3a.sup.Me], [3b.sup.Me], and [3e.sup.Me]. Calculations show that the different nature of the frontier orbitals of [3a.sup.R] compared to those of [3b.sup.R] and [3e.sup.R], might account for the different reactivities of these compounds. Moreover, the weak donor character of [3b.sup.R] and [3e.sup.R] towards molecular di-iodine, estimated by FT-Raman measurements is in agreement with the calculated NBO-charge distribution. Key words: selenation, selenoparabanic derivatives, crystal structure, DFT calculations.

Using empirical potentials derived from fitting the vibrational frequencies of a group of silicates and oxides, and crystallographic information, a Born-von Karman rigid-ion lattice-dynamical model has been applied to the whole Brillouin zone in beryl. The Raman and infrared spectra are satisfactorily reproduced and interpreted by these calculations; there is also very good agreement with atomic displacement parameters derived from accurate crystal-structure refinement by various authors and with experimental values of thermodynamic functions for the anhydrous phase at different temperatures. The agreement of our calculations with experimental data of independent origin and nature demonstrates the potential of such a procedure.