Ternary Rhodium Borides A3Rh5B2 (A = Mg,Sc) and Quaternary Derivatives A2MRh5B2. Preparation,Crystal Structure (M = Main Group and 3 d Elements), and Magnetism (M = Mn,Fe)

The new ternary rhodium borides Mg₃Rh₅B₂ and Sc₃Rh₅B₂ (P4/mbm, Z = 2; a = 943.4(1) pm, c = 292.2(1) pm and a = 943.2(1) pm, c = 308.7(1) pm, respectively) crystallize with the Ti₃Co₅B₂ type structure. Mg and Sc may in part be substituted by a variety of elements M. For M = Si and Fe, homogeneity ranges were found according to A_3–xM_xRh₅B₂ with 0 ≤ x ≤ 1.0 for A = Sc and with x up to 1.5 for A = Mg. Quaternary compounds with x = 1 (A₂MRh₅B₂: A/M in short) were prepared with M = Be, Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Sn (Co, Ni only with A = Mg; Sn only with A = Sc; P, As with deficiencies). Single crystal X‐ray investigations show an ordered substitutional variant of the Ti₃Co₅B₂ type in which the M atoms are arranged in chains along [001] with intrachain and interchain M–M distances of about 300 pm and 660 pm, respectively. Measuring the magnetisation (1.7 K–800 K) of the phases Mg/Mn, Sc/Mn, Mg/Fe, and Sc/Fe reveals antiferromagnetic interactions in the first and dominating ferromagnetic intrachain interactions in the remaining ones. Interchain interactions of antiferromagnetic nature are evident in Sc/Mn and Mg/Fe leading to metamagnetism below T_N = 130 K, while Sc/Fe behaves ferromagnetically below T_C = 450 K. The overall trend towards stronger ferromagnetic interactions with increasing valence electron concentration is obvious.     

Reactions of Ammonium Alkylene Dithiophosphates with Phosphorus Trichloride and Thiophosphoryl Chloride *

Phosphorus trichloride and thiophosphoryl chloride derivatives of alkylene dithiophosphates of the type PCl_{3 ? n} () _n and P(S)Cl_{3? n} () _n (where G = -CH₂CH₂CHMe-, -CMe₂CMe₂-, -CH₂CH₂CH₂CH₂- and -CMe₂CH₂ CHMe-, n = 1, 2, 3] have been synthesized for the first time by reacting the ammonium salt of alkylene dithiophosphoric acid with phosphorus trichloride and thiophosphoryl chloride in different stoichiometric ratios under anhydrous reaction conditions. The newly synthesized derivatives are either colorless liquids or viscous semisolids, hygroscopic in nature and are soluble in common organic solvents. These are characterized by elemental analysis, molecular weight determinations and physicochemical studies IR, NMR (¹H and ³¹P). On the basis of above studies the formation of P-S-P and S = P–S–P(S) chemical linkages have been established. ²³¹P NMR studies provide convincing evidence regarding the chemical bonding mode in these derivatives.     

Determination of minor and trace elements in <Emphasis Type="Italic">Trifala</Emphasis> - a herbal preparation

Summary Eight different brands of Trifala and its three constituents, Amalaki (Embilica officinalis), Bibhitaki (Terminalia bellirica) and Haritaki (T.chebula) were analyzed for 6 minor (Na, K, Mg, Ca, Cl and P) and 19 trace (Al, Ba, Br, Co, Cr, Cs, Fe, Eu, Hf, Hg, La, Mn, Rb, Sb, Sc, Se, Th, V and Zn) elements by instrumental neutron activation analysis (INAA). Two candidate reference materials Tea Leaves (TL-1) and Mixed Polish Herbs (MPH-2) were also analyzed as a part of Intercomparison Study besides several reference materials (RMs) for quality control. The samples along with RMs were irradiated with thermal neutrons in APSARA/Dhruva reactors at BARC, Mumbai and their activity measured on HPGe detector and 8K MCA system. Also Ni, Cu, Cd and Pb contents were determined by AAS. Bibhitaki is found to be enriched in Fe (0.98 mg/g), P (1.10 mg/g), Co (1.74 mg/g) and Se (240 ng/g) including alkali and alkaline earth metals. Availability of many nutrient elements such as Mg, Ca, K, Fe, and Se in Trifala is attributed to its usefulness in the treatment of liver disorder, heart ailments, hepatic diseases and cancer, as expectorant, powerful eye rejuvenator and an antioxidant.     

Synthese und Kristallstruktur von Hydrogenselenaten zweiwertiger Metalle – M(HSeO4)2 (M = Mg,Mn, Zn) und M(HSeO4)2 · H2O (M = Mn,Cd)

Synthesis and Crystal Structure of Hydrogen Selenates of Divalent Metals – M(HSeO₄)₂ (M = Mg, Mn, Zn) and M(HSeO₄)₂ · H₂O (M = Mn, Cd) New hydrogen selenates M(HSeO₄)₂ (M = Mg, Mn, Zn) and M(HSeO₄)₂ · H₂O (M = Mn, Cd) have been synthesized using MSeO₄ (M = Mg, Mn, Zn, Cd) and 90% selenic acid as starting materials. The crystal structures have been determined by X-ray single crystal crystallography. The compounds M(HSeO₄)₂ (M = Mg, Zn) belong to the structure type of Mg(HSO₄)₂, whereas Mn(HSeO₄)₂ forms a new structure type. Both hydrogen selenate monohydrates are isotypic to Mg(HSO₄)₂ · H₂O. In all compounds the metal atoms are octahedrally coordinated by oxygen atoms of different HSeO₄-tetrahedra. In the HSeO₄-tetrahedra the Se–OH-distances (mean value 1.70 Å) are about 0.1 Å longer than Se–O-distances (mean value 1.62 Å). In the structure of M(HSeO₄)₂ (M = Mg, Zn) there are zigzag chains of hydrogen bonded HSeO₄-tetrahedra. The structure of Mn(HSeO₄)₂ is characterized by chains of HSeO₄-tetrahedra in form of screws. Hydrogen bonds from and to water molecules connect double layers of MO₆-octahedra and HSeO₄-tetrahedra in the structures of M(HSeO₄)₂ · H₂O.     

Hexafluoropropylene Oxide–Alcohol: A Convenient System for Silica Dissolution

Abstract

A new method of silica dissolution is described. It involves the formation of a stable SiF₄ · n ROH complex (1, 1a) just from SiO₂ and anhydrous alcoholic HF generated in situ from commercially available hexafluoropropene oxide. Alcoholic SiF₄ complexes can be easily converted to different organosilicon compounds of the type SiF₄L₂ and (LH)₂SiF₆ [L = 1,10-phenantroline (2a), 2,2′-dipyridyl (2b), Me₂SO (2c), pyridine (2d), triethanolamine (3a)]. Different silica-containing compounds can be used in this strategy—silicagel, sand, alumosilicates, and even rice husk.

GRAPHICAL ABSTRACT     

Two Glutarato Bridged Coordination Polymers: ${_{\infty}^1}${[Mn(phen)]2L4/2} and ${_{\infty}^1}${[Zn(phen)(H2O)]L2/2}·H2O with H2L = Glutaric Acid

Two new glutarato bridged coordination polymers {[Mn(phen)]₂(C₅H₆O₄)_4/2} ( 1 ) and {[Zn(phen)(H₂O)](C₅H₆O₄)_2/2}· H₂O ( 2 ) were structurally characterized on the basis of single crystal X‐ray diffraction data. Crystal data: ( 1 ) P2/c (no. 13), a = 10.340(2)Å, b = 10.525(2)Å, c = 13.891(2)Å, β = 98.31(1)°, U = 1495.9(5)ų, Z = 2; ( 2 ) P2₁/n (no. 14), a = 6.738(1)Å, b = 25.636(3)Å, c = 10.374(1)Å, β = 106.13(1)°, U = 1721.4(4)ų, Z = 4. Complex 1 consists of 1D ribbon‐like {[Mn(phen)]₂(C₅H₆O₄)_4/2} chains, in which the [Mn(phen)] units were interlinked by glutarato ligands to generate 8‐ and 16‐membered rings. The Mn atoms are octahedrally coordinated by two N atoms of one phen ligand and four O atoms of three glutarato ligands with d(Mn‐N) = 2.270, 2.276Å, d(Mn‐O) = 2.114—2.283Å. Through the interchain π‐π stacking interactions, the 1D chains are assembled into 2D puckered layers, which are further held together by interlayer π‐π stacking interactions into a 3D network. Complex 2 is built up by 1D {[Zn(phen)(H₂O)](C₅H₆O₄)_2/2} linear chains and hydrogen bonded H₂O molecules. The Zn atoms are coordinated by two N atoms of one phen ligand and three O atoms of one H₂O molecule and two glutarato ligands to form slightly elongated trigonal bipyramids with the water O atom and one phen N atom at the apical positions (d(Zn‐N) = 2.101, 2.168Å, d(Zn‐O) = 1.991—2.170Å). The 1D linear chains result from [Zn(phen)(H₂O)] units bridged by bis‐monodentate glutarato ligands. The resulting 1D chains are assembled by π‐π stacking interactions into 2D layers, between which the hydrogen bonded H₂O molecules are situated.     

Triphenylphosphinoxid (L) als Solvens und Ligand für Metallphthalocyaninate; Synthese und Struktur von [{Li(L)}2(μ‐pc)], [Li(L)4][Lipc] · Solvat, [Mg(L)pc] · Solvat und [Zn(L)pc] · Solvat

Triphenylphosphine Oxide (L) as Solvent and Ligand for Metallophthalocyaninates; Synthesis and Structure of [{Li(L)}₂(μ‐pc)], [Li(L)₄][Lipc] · Solvate, [Mg(L)pc] · Solvate, and [Zn(L)pc] · Solvate Triphenylphosphine oxide (L) coordinates to metallophthalocyaninates of Li, Mg and Zn at 300 °C. After purification and recrystallization in different solvents the very soluble and stable title compounds have been isolated and structurally characterized. In [{Li(L)}₂(μ‐pc)], the Li atom lies in a distorted tetragonal pyramid of four isoindole N atoms (N_i) at a distance varying between 2.163(5) and 2.301(5) Å, and an O atom at 1.863(5) Å. In [Li(L)₄] · [Lipc] · S, the Li atom of the cation coordinates four O atoms in a distorted tetrahedral arrangement at a distance varying from 1.887(9) to 1.953(9) Å, while the Li atom of the anion is in a quasi quadratic planar geometry of four N_i atoms (1.951(9)–1.977(9) Å) with the Li atom being displaced by 0.15 Å out of the (N_i)₄ plane. The structural data of the distorted tetragonal pyramidale Mg(N_i)₄O moiety in [Mg(L)pc] and the solvates [Mg(L)pc] · S (S = CH₂Cl₂, thf, 2py) generally do not vary significantly: Mg–N_i/2.035(3) –2.061(3) Å, Mg–O/1.955(2)–2.000(3) Å. The Mg atom is displaced by ca. 0.52 Å out of the (N_i)₄ plane towards the O atom and the Mg–O–P moiety is bent (ca. 153°). [Zn(L)pc] · S crystallizes as a mixed crystal of equal parts of the conformer with a bent (155.1(3)°) and that of a quasi linear Zn–O–P moiety (174.2(3)°). Structural data of the Zn(N_i)₄O moiety: (Zn–N_i)_av: 2.024/2.013 Å; Zn–O: 2.050(4)/2.081(4) Å; Zn–(N_i)₄: 0.40/0.33 Å. In the crystal, the Mg and Zn derivates aggregate in double layers forming pairs. The pc ligands in the triclinic complexes with good overlap of the neighbouring pc ligands are in a waving conformation, while those in the monoclinic complexes with weak overlap are in a concave conformation.     

CsMn2P2, ein Mangan(II,III)‐phosphid mit der BaZn2P2‐Struktur. Mit einem Beitrag zum BaAl4‐Strukturtyp

CsMn₂P₂, a Manganese(II, III) Phosphide with BaZn₂P₂ Structure. With a Contribution to the BaAl₄ Structure Type CsMn₂P2₂is formed by the reaction of Cs₄P₆ with Mn and red phosphorus (Nb ampoule; 1073 K) as black platelets. The compound is paramagnetic following the Curie‐Weiss law above 110 K (μ = 4.81 B.M. / CsMn₂P₂; θ = —79 K) and orders antiferromagnetically below 110 K. The magnetic moment corresponds with the ratio Mn^II : Mn^III = 1:1. CsMn₂P₂ is isotypic with BaZn₂P₂ (tI10; I4/mmm; a = 4.098(1) Å, c = 14.215(4) Å, d(Mn—P) = 2.387(1) Å (4×), d(Cs—P) = 3.718(2) Å (8×)), and shows, therefore, no P—P‐bonds. The different regions of the BaAl₄ (ThCr₂Si₂) structure type are analysed and parameterized once more.     

Some aspects of element distribution inBetula alba, a contribution to representative sampling of terrestrial plants for multi-element analysis

Summary The leaves of six differently aged birch trees (Betula alba), growing under slightly varying soil conditions, were collected representatively. The elements Ca, K, Mg and Zn were determined by different analytical methods (AAS and AES/ICP). The data sets obtained were in good agreeent with each other. The biological variances of Al, Ba, Ca, Cu, Fe, K, Mg, P and Zn between leaves of different trees were less than 30%, with the exception of phosphorus (38%). Ca, K, Mg, Mn and Zn show an increase of between 50%–70% depending on the height of the trees. The developed sampling procedure (5–10 trees per ecosystem) can be adapted to produce a representative sampling design on population level.

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Einige Aspekte der Elementverteilung inBetula alba, ein Beitrag zur repräsentativen Probenahme von terrestrischen Pflanzen für die Multielement-Analyse

     

On the Use of the Optothermal Window Technique for the Determination of Low Concentrations of Chromium (VI) and Phosphorus in Water

Abstract

In this work we report about the use of the Optothermal Window (OW) technique, actually a variant of Photoacoustic Spectroscopy, combined with well-proven colorimetric methods to the determination of low concentrations of pollutants in water. As a first approach, chromium (VI) and phosphorus were determined in distilled water samples. The determination of Cr (VI) and P species in environmental and biological systems is currently of considerable interest due to the toxicity of their compounds to live organisms. Their maximum allowed values in drinking water were well discriminated in our experiments as well as the limits of optical spectrophotometric measurements. The detection limit in our measurements was 0.1 μmol/L P-PO₄ ^3- for phosphorus at 632.8 nm and 0.2 μmol/L for chromium (VI) at 514 nm.     

Synthesis and Characterization of Side Group–Modified Cyclotetraphosphazene Derivatives

Abstract

Two novel cyclotetraphosphazene derivatives were synthesized by the reaction of octachlorocyclotetraphosphazene with the potassium salt of 4-hydroxybenzaldehyde, and subsequent reduction of aldehyde groups to alcohol groups using sodium borohydride. The bromination reaction was carried out using PBr₃ to give N₄P₄(OC₆H₄-p-CH₂Br)₈ (4). This compound was employed in reaction with imidazole or morpholine to produce eight-armed, star-branched title compounds. The target compounds were characterized by ¹H, ³¹P, and ¹³C NMR as well as IR and ESI-MS. The Cu complex of 5a was effective in oxidative cleavage reactions.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT     

Mg7(AsO4)2(HAsO4)4: a new magnesium arsenate with a very strong hydrogen bond

A new compound, heptamagnesium bis­(arsenate) tetrakis(hydrogenarsenate), Mg₇(AsO₄)₂(HAsO₄)₄, was synthesized by a hydro­thermal method. The structure is based on a three‐dimensional framework of edge‐ and corner‐sharing MgO₆, MgO₄(OH)₂, MgO₅, AsO₃(OH) and AsO₄ polyhedra. Average Mg—O and As—O bond lengths are in the ranges 2.056–2.154 and 1.680–1.688 Å, respectively. Each of the two non‐equivalent OH groups is bonded to both an Mg and an As atom. One OH group is involved in a very short hydrogen bond [O⋯O = 2.468 (3) Å]. The formula unit is centrosymmetric, with all atoms in general positions except for one Mg atom, which has site symmetry . The compound is isotypic with Mn₇(AsO₄)₂(HAsO₄)₄ and M₇(PO₄)₂(HPO₄)₄, where M is Fe, Co or Mn.     

Si3S-, Si3Se-, Si3Te-Bicyclo[1.1.0]butanes and Si3S2-Bicyclo[1.1.1]pentane

The reaction of trisilirene 1 with propylene sulfide or elemental sulfur produced Si₃S-bicyclo[1.1.0]butane 2, which underwent Si–Si insertion of a second S atom forming Si₃S₂-bicyclo[1.1.1]pentane 3. Analogous reactions of 1 with elemental Se or Te resulted in the formation of heavier analogues of 2, namely, Si₃Se-bicyclo[1.1.0]butane 4 and Si₃Te-bicyclo[1.1.0]butane 5.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT     

Synthesis of New Benzylic Di-, Tri-, and Tetraphosphonic Acids as Potential Chelating Agents

Abstract

New di-, tri-, and tetraphosphonic acids were synthesized starting from four o-hydroxymethyl phenol derivatives and obtained in three steps in good overall yield. The phosphonic acids were isolated and purified using semi-preparative C₁₈ HPLC column. The new compounds were characterized using different spectroscopic methods (¹H, ¹³C, and ³¹P NMR; ESI MS; and MSⁿ, IR).

GRAPHICAL ABSTRACT     

Ce20Mg19Zn81: a new structure type with a giant cubic cell

Icosacerium nonadecamagnesium henoctacontazinc, Ce₂₀Mg₁₉Zn₈₁, synthesized by fritting of the pure elements with subsequent arc melting, crystallizes with an unusually large cubic unit cell [space group F3m, a = 21.1979 (8) Å] and represents a new structure type among the technologically important family of ternary rare earth–transition metal–magnesium intermetallics. The majority of atoms (two Ce and five Zn) display .3m site symmetry, two Ce and one Mg atom occupy three 2.mm positions, one Mg and one Zn have 3m site symmetry, one Mg and three Zn atoms sit in ..m positions, and one Zn atom is in a general position. The Ce₂₀Mg₁₉Zn₈₁ structure can be described using the geometric concept of nested polyhedral units, by which it consists of four different polyhedral units, viz.A (Zn+Zn₄+Zn₄+Zn₁₂+Ce₆), B (Mg+Zn₁₂+Ce₄+Zn₂₄+Ce₄), C (Zn₄+Zn₁₂+Mg₆) and D (Zn₄+Zn₄+Mg₁₂+Ce₆), with the outer construction unit being an octahedron or tetrahedron. All interatomic distances in the structure indicate metallic‐type bonding.