scholarly journals The astrophyllite supergroup: nomenclature and classification

2017 ◽  
Vol 81 (1) ◽  
pp. 143-153 ◽  
Author(s):  
Elena Sokolova ◽  
Fernando Cámara ◽  
Frank C. Hawthorne ◽  
Marco E. Ciriotti
Keyword(s):  
General Formula ◽  
Structural Unit ◽  
Main Structural Unit ◽  
Dominant Cation

AbstractHere we report a nomenclature and classification for the astrophyllite-supergroup minerals. The HOH block is the main structural unit in all astrophyllite-supergroup structures; it consists of three H–O–H sheets where the T4O12 astrophyllite ribbons occur in the H sheets. In each structure, HOH blocks alternate with I (Intermediate) blocks along [001]. The twelve minerals of the astrophyllite supergroup are divided into three groups based on (1) the type of self-linkage of HOH blocks, i.e. (a) HOH blocks link directly where they share common vertices of D octahedra, or (b) HOH blocks do not link directly; and (2) the dominant cation of the O sheet (the C group: C7 apfu). In the astrophyllite group (HOH blocks connect via D– XDP–D bridges, Fe2+ is dominant at C7), there are six minerals: astrophyllite, niobophyllite, zircophyllite, tarbagataite, nalivkinite and bulgakite. In the kupletskite group (HOH blocks connect via D–XDP–D bridges, Mn2+ is dominant at C7), there are three minerals: kupletskite, niobokupletskite and kupletskite-(Cs). In the devitoite group (HOH blocks do not connect via D–XDP–D bridges), there are three minerals: devitoite, sveinbergeite and lobanovite. The general formula for the astrophyllite-supergroup minerals is of the form A2pBrC7D2(T4O12)2IXD2OXA4OXDnPWA2, where C [cations at the M(1–4) sites in the O sheet] = Fe2+, Mn, Na, Mg, Zn, Fe3+, Ca, Zr, Li; D (cations in the H sheets) = [6,5]Ti, Nb, Zr, Sn4+ , [5]Fe3+, Mg, Al; T = Si, minor Al; A2pBrIWA2 (I block) where p = 1,2; r = 1,2; A = K, Cs, Ba, H2O, Li, Rb, Pb2+, Na,□; B = Na, Ca, Ba, H2O,□; I represents the composition of the central part of the I block, excluding peripheral layers of the form A2pBrWA2, e.g. (PO4)2(CO3) (devitoite); XDO = O; XAO = OH, F; XDP = F, O, OH, H2O,□, where n = 0, 1, 2 for (XDP)n; WA = H2O,□.

The seidozerite supergroup of TS-block minerals: nomenclature and classification, with change of the following names: rinkite to rinkite-(Ce), mosandrite to mosandrite-(Ce), hainite to hainite-(Y) and innelite-1T to innelite-1A

2017 ◽  
Vol 81 (6) ◽  
pp. 1457-1484 ◽  
Author(s):  
E. Sokolova ◽  
F. Cámara
Keyword(s):  
General Formula ◽  
Structural Unit ◽  
Alkaline Earth ◽  
Formula Unit ◽  
Minimal Cell ◽  
Titanium Silicate ◽  
Octahedral Sheet ◽  
And Topology ◽  
Block Structures ◽  
Alkaline Earth Cations

AbstractHere we report a nomenclature and classification for the seidozerite-supergroup minerals. The TS (Titanium-Silicate) block is the main structural unit in all seidozerite-supergroup structures; it consists of a central O (O = Octahedral) sheet and two adjacent H (H = Heteropolyhedral) sheets where Si2O7groups occur in the H sheets. The TS block is characterized by a planar minimal cell based on translation vectors, t1and t2, the lengths of these vectors are t1 ≈ 5.5 and t2 ≈ 7 Å, and t1 ^ t2 is close to 90°. The forty-five minerals of the sedozerite supergroup are divided into four groups based on the content of Ti and topology and stereochemistry of the TS block: in rinkite, bafertisite, lamprophyllite and murmanite groups, Ti (+ Nb + Zr + Fe3++Mg + Mn) = 1, 2, 3 and 4 apfu (atoms per formula unit), respectively. All TS-block structures consist either solely of TS blocks or of two types of block: the TS block and an I (Intermediate) block that comprises atoms between two TS blocks. Usually, the I block consists of alkali and alkaline-earth cations, H2O groups and oxyanions (PO4)3-, (SO4)2-and (CO3)2-.The general formula of the TS block is as follows AP2BP2MH2MO4(Si2O7)2X4+n, where MH2and MO4= cations of the H and O sheets; MH = Ti, Nb, Zr, Y, Mn, Ca + REE, Ca;MO = Ti, Zr, Nb, Fe3+, Fe2+, Mg, Mn, Zn, Ca, Na; AP and BP = cations at the peripheral (P) sites = Na, Ca + REE, Ca, Zn, Ba, Sr, K; X = anions = O, OH, F, H2O; XO4+n=XO4 +XPn, n = 0, 1, 1.5, 2, 4; XP= XPMand XPA= apical anions of MH and AP cations at the periphery of the TS block.

The Collagenic Molecular Structural Unit of Solid State Complexes

1971 ◽  
Vol 29 ◽  
pp. 478-479
Author(s):  
Kenneth M. Richter ◽  
John A. Schilling
Keyword(s):  
Molecular Weight ◽  
Solid State ◽  
Structural Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naoh Treatment

The structural unit of solid state collagen complexes has been reported by Porter and Vanamee via EM and by Cowan, North and Randall via x-ray diffraction to be an ellipsoidal unit of 210-270 A. length by 50-100 A. diameter. It subsequently was independently demonstrated by us in dog tendon, dermis, and induced complexes. Its detailed morphologic, dimensional and molecular weight (MW) aspects have now been determined. It is pear-shaped in long profile with m diameters of 57 and 108 A. and m length of 263 A. (Fig. 1, tendon, KMnO4 fixation, Na-tungstate; Fig. 2a, schematic of unit in long, C, and x-sectional profiles of its thin, xB, and bulbous, xA portions; Fig. 2b, tendon essentially unmodified by ether and 0.4 N NaOH treatment, Na-tungstate). The unit consists of a uniquely coild cable, c, of ṁ 22.9 A. diameter and length of 2580-3316 A. The cable consists of three 2nd-strands, s, each of m 10.6 A.

X-ray Structure Refinement and Vibrational Spectroscopy of Ca8Gd2 (PO4)6 O2

2013 ◽  
Vol 12 (10) ◽  
pp. 719-726
Author(s):  
R. Ayadi ◽  
Mohamed Boujelbene ◽  
T. Mhiri
Keyword(s):  
Solid State ◽  
General Formula ◽  
Vibrational Spectroscopy ◽  
Powder Diffraction ◽  
Infrared Spectra ◽  
Solid State Reaction ◽  
Structure Refinement ◽  
Unit Cell ◽  
Cell Group ◽  
X Ray

The present paper is interested in the study of compounds from the apatite family with the general formula Ca10 (PO4)6A2. It particularly brings to light the exploitation of the distinctive stereochemistries of two Ca positions in apatite. In fact, Gd-Bearing oxyapatiteCa8 Gd2 (PO4)6O2 has been synthesized by solid state reaction and characterized by X-ray powder diffraction. The site occupancies of substituents is0.3333 in Gd and 0.3333 for Ca in the Ca(1) position and 0. 5 for Gd in the Ca (2) position.  Besides, the observed frequencies in the Raman and infrared spectra were explained and discussed on the basis of unit-cell group analyses.

Toxicity of Para-Chloro Substituted Benzene Derivatives in the Microtox™ Test

1985 ◽  
Vol 20 (2) ◽  
pp. 36-43 ◽  
Author(s):  
Klaus L.E. Kaiser ◽  
Juan M. Ribo ◽  
Brian M. Zaruk
Keyword(s):  
General Formula ◽  
Functional Group ◽  
Structural Parameters ◽  
Systematic Investigation ◽  
Photobacterium Phosphoreum ◽  
Benzene Derivatives ◽  
Quantitative Structure ◽  
Chlorinated Benzenes ◽  
Chloro Derivatives ◽  
Derivatives Of

Abstract This paper gives the results of part of a systematic investigation into contaminant toxicity to Photobacterium phosphoreum in the Microtox™ test. Reported are the toxicity values for 39 para-chloro substituted benzene derivatives of the general formula l-Cl-C6h4-4-X=CH2CH(NH2)COOH, F, SO2NH2, OCH2COOH, CH2COOH, CONHNH2, NHCOCH3, CONH2, CH=CHCOOH, SeOOH, CH2NH2, CH2CH2NH2, NO2, H, CF3, CHO, CH2OH, OH, CH3, CCl3, COCH3, COOH, NH2, SO2C6H5, Cl, CH2COCH3, COCl, CN, OCH3, NCO, NHCH3, I, COC6H5, CH2Cl, SH, CH2SH, NCS, CH2CN and SO2C6H4Cl. Except for the last compound, whose solubility is below the required concentration, the toxicities increase in the presented order with a total range of more than three orders of magnitude. The data are discussed in terms of quantitative structure-toxicity correlations with compound-specific structural parameters. In combination with a previously developed submodel on chlorinated benzenes, phenols, nitrobenzenes and anilines, the observed relationships allow the prediction of the toxicity of some 780 possible chloro derivatives of the general formula C6H5-nClnX, where n=<5 and X is a functional group as listed above.

Synthesis of isomeric 1,1'-phenylene-bis(6-azauracil-5-carbonitriles)

1990 ◽  
Vol 55 (12) ◽  
pp. 2967-2976 ◽  
Author(s):  
Jan Slouka
Keyword(s):  
General Formula ◽  
Mutual Distance ◽  
Planar Molecules ◽  
Amino Derivatives

The described synthesis of all three isomeric 1,1'-phenylene-bis(6-azauracil-5-carbonitriles) IVa-IVc starts from the respective 1-nitrophenyl-6-azauracil-5-carbonitriles Ia-Ic which were reduced to the corresponding amino derivatives IIa-IIc, diazotized, and coupled with ethyl cyanoacetylcarbamate to give the isomeric hydrazones IIIa-IIIc which were finally cyclized to the title compounds containing two 6-azauracil rings. A general formula is presented for calculation of mutual distance of arbitrary atoms in any planar molecules.

A Modern Concept of the Cell as a Structural Unit

1940 ◽  
Vol 74 (750) ◽  
pp. 5-24 ◽  
Author(s):  
George A. Baitsell
Keyword(s):  
Structural Unit ◽  
Modern Concept

The Coordination Chemistry of Phosphoryl Compounds Containing the — N(CH3)2 Group, Part VIII

1972 ◽  
Vol 27 (7) ◽  
pp. 759-763 ◽  
Author(s):  
M. W. G. De Bolster ◽  
W. L. Groeneveld
Keyword(s):  
Coordination Chemistry ◽  
General Formula ◽  
Ligand Field ◽  
Chemical Analyses ◽  
X Ray ◽  
Physical Measurements ◽  
Ligand Field Spectra ◽  
Chloride Adduct ◽  
Ligand Field Parameters ◽  
Group Part

A number of new solvates and adducts containing bisphenyldimethylaminophosphine oxide is reported. The solvates have the general formula M[(C6H5)2P(O)N(CH3)2]42+(anion-)2, in which M = Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn and Cd, and the anions are ClO4- and BF4-. The adducts have the general formula M[(C6H5)2P(O)N(CH3)2]2Cl2, where M stands for the same series of metals.The compounds are characterized and identified by chemical analyses and physical measurements.Ligand-field and vibrational spectra have been investigated; values for the ligand-field parameters are reported. It is concluded that coordination takes place via the oxygen atom of the ligand.X-ray powder patterns were used in combination with ligand-field spectra to deduce the coordination around the metal ions.The interesting behaviour of the nickel (II) chloride adduct upon heating is discussed and it is shown that both a square pyramidal and a tetrahedral modification exists.

scholarly journals An investigation of polyhedral deformation in two mixed-metal diarsenates: SrZnAs2O7and BaCuAs2O7

2015 ◽  
Vol 71 (4) ◽  
pp. 330-337 ◽  
Author(s):  
Sabina Kovač ◽  
Ljiljana Karanović ◽  
Tamara Đorđević
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
General Formula ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Open Framework ◽  
Geometrical Characteristics ◽  
Barium Copper

Two isostructural diarsenates, SrZnAs2O7(strontium zinc diarsenate), (I), and BaCuAs2O7[barium copper(II) diarsenate], (II), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. The three-dimensional open-framework crystal structure consists of corner-sharingM2O5(M2 = Zn or Cu) square pyramids and diarsenate (As2O7) groups. Each As2O7group shares its five corners with five differentM2O5square pyramids. The resulting framework delimits two types of tunnels aligned parallel to the [010] and [100] directions where the large divalent nine-coordinatedM1 (M1 = Sr or Ba) cations are located. The geometrical characteristics of theM1O9,M2O5and As2O7groups of known isostructural diarsenates, adopting the general formulaM1IIM2IIAs2O7(M1II= Sr, Ba, Pb;M2II= Mg, Co, Cu, Zn) and crystallizing in the space groupP21/n, are presented and discussed.

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