Biomedical subjects

Matthias Weil

Publications and source records attributed to Matthias Weil.

9 recordsLinked to original sources

PubMed2005

Ag2Hg2(TeO4)3.

Red single crystals of disilver(I) dimercury(II) tris[tetraoxotellurate(VI)], Ag2Hg2(TeO4)3, were obtained under hydrothermal conditions at 523 K. The structure is built up of infinity1[(TeO2/1O4/2)({TeO2/1O2/2}2O4/2)] chains, with an overall composition [TeO4]2-, that run parallel to the crystallographic a axis. Distorted AgO6 and HgO6 polyhedra (the latter with two short and nearly collinear Hg-O bonds) link the tellurate chains into a three-dimensional network. Except for one Te atom situated on an inversion center, all atoms occupy general positions.

Journal Article↗

PubMed2005

Hydrothermal single-crystal growth in the systems Ag/Hg/X/O (X = VV, AsV): crystal structures of (Ag3Hg)VO4, (Ag2Hg2)3(VO4)4, and (Ag2Hg2)2(HgO2)(AsO4)2 with the unusual tetrahedral cluster cations (Ag3Hg)3+ and (Ag2Hg2)4+ and crystal structure of AgHgVO4.

Single crystals of (Ag3Hg)VO4 (I), (Ag2Hg2)3(VO4)4 (II), AgHgVO4 (III), and (Ag2Hg2)2(HgO2)(AsO4)2 (IV) were grown under hydrothermal conditions (250 degrees C, 5 d) from starting mixtures of elementary mercury, silver nitrate, ammonium vanadate, and disodium hydrogenarsenate, respectively. All crystal structures were determined from X-ray diffraction data, and their chemical compositions were confirmed by electron microprobe analysis. I crystallizes in the tillmannsite structure, whereas II-IV adopt new structure types: (I) I4, Z = 2, a = 7.7095(2) A, c = 4.6714(2) A, 730 structure factors, 24 parameters, R[F2 > 2sigma(F2)] = 0.0365; (II) I42d, Z = 4, a = 12.6295(13) A, c = 12.566(3) A, 1524 structure factors, 55 parameters, R[F2 > 2sigma(F2)] = 0.0508; (III) C2, Z = 4, a = 9.9407(18) A, b = 5.5730(8) A, c = 7.1210(19) A, beta = 94.561(10) degrees , 1129 structure factors, 48 parameters, R[F2 > 2sigma(F2)] = 0.0358; (IV) P31c, Z = 2, a = 6.0261(9) A, c = 21.577(4) A, 1362 structure factors, 52 parameters, R[F2 > 2sigma(F2)] = 0.0477. The most striking structural features of I, II, and IV are the formation of tetrahedral cluster cations (Ag3Hg)3+ and (Ag2Hg2)4+, respectively, built of statistically distributed Ag and Hg atoms with a metal-metal distance of about 2.72 A. The electronic structure of these clusters can formally be considered as two-electron-four-center bonding. The crystal structure of III differs from the protrusive structure types insofar as silver and mercury are located on distinct crystallographic sites without a notable metal-metal interaction >3.55 A. All crystal structures are completed by tetrahedral oxo anions XO4(3-) (X = VV, AsV) and for IV additionally by a mercurate group, HgO2(2-).

Journal Article↗

PubMed2005

Vibrational spectra of Hg3TeO6 and Hg2TeO5.

The infrared and Raman spectra of the crystalline hexaoxotellurates Hg3TeO6 and Hg2TeO5 were recorded and discussed on the basis of a site symmetry analysis derived from known structural data. Approximate values for the Te-O bond force constants are reported and some comparisons with related species are made.

Hydrogen Bonding↗

PubMed2004

Preparation and characterization of dimercury(I) monofluorophosphate(V), Hg2PO3F: crystal structure, thermal behavior, vibrational spectra, and solid-state 31P and 19F NMR spectra.

Single crystals of anhydrous dimercury(I) monofluorophosphate(V), Hg(2)PO(3)F (1), were obtained by cooling diluted aqueous Hg(2)(NO(3))(2) and (NH(4))(2)PO(3)F solutions from 85 degrees C to room temperature. Compound 1 crystallizes with eight formula units in the orthorhombic space group Ibam (No. 72) and lattice parameters a = 9.406(2) A, b = 12.145(3) A, c = 8.567(2) A. It adopts a new structure type even though a topological relation with dimercury(I) sulfate, Hg(2)SO(4), is established. The crystal structure of 1 (R(F(2) > 2sigma(F(2)) = 0.0353) exhibits Hg(2)(2+) dumbbells and discrete PO(3)F(2)(-) anions as single building units which are organized in a layered assembly parallel to (100). The symmetric Hg(2)(2+) dumbbell shows a typical Hg-Hg distance of 2.5051(9) A, and for each Hg atom, three Hg-O distances are found, ranging from 2.327(6) to 2.476(5) A. No interactions between Hg and F atoms are realized. The latter is exclusively bonded to the phosphorus atom at a distance d(P-F) = 1.568(8) A which is considerably longer than the P-O distances with a mean of 1.515 A. Compound 1 was further characterized by vibrational spectroscopy (Raman and IR) in the spectral range between 4000 and 50 cm(-)(1), thermal analysis (TG, DSC) up to 650 degrees C which revealed Hg(2)(P(2)O(7)) and Hg(3)(PO(4))(2) as thermal decomposition products, and (19)F and (31)P solid-state NMR spectroscopy. The value for the P-F coupling constant in 1 is J(PF) = -1072 Hz at 20 degrees C. The absolute sign of J(PF) is negative.

Journal Article↗

PubMed2004

The high-temperature modification of zinc catena-polyphosphate, beta-Zn(PO3)2.

Single crystals of the high-temperature modification of zinc catena-polyphosphate, beta-Zn(PO(3))(2), were grown from a melt and quenched from 1093 K to room temperature. The structure was solved from single-crystal X-ray diffraction data and is built of corrugated (PO(3))( infinity ) polyphosphate chains, which extend along the c direction with an eight-tetrahedra repeat. Slightly distorted [ZnO(4)] tetrahedra link the polyphosphate chains into a three-dimensional network.

Journal Article↗

PubMed2002

The channel structure of the mercury(II) selenite(IV) oxide hydrate HgSeO3.HgO.1/6H2O.

The main building units of the title compound, dimercury(II) selenite(IV) oxide hydrate, are strongly distorted [Hg1O(6)] and [Hg2O(7)] polyhedra, and a pyramidal Se(IV)O(3) group. Slightly corrugated hexagonal rings made up of six [Hg1O(6)] octahedra spread parallel to the ab plane and are connected via [Hg2O(7)] polyhedra parallel and perpendicular to this direction, which results in a three-dimensional arrangement with channels propagating parallel to the c axis. The Se(IV)O(3) groups are situated below and above the rings and bridge both types of Hg atoms. The non-bonding orbitals are stereochemically active and protrude into the channels of the three-dimensional network. Additional water molecules are located at the centres of the channels and show weak interactions with the Se(IV) lone pairs and the O atoms of the Se(IV)O(3) groups.

Journal Article↗

PubMed2002

The ordered hydrocerussite-type structure of (PbCO3)2.BaF2.

Single crystals of synthetic (PbCO(3))(2).BaF(2), bis[lead(II) carbonate] barium difluoride, have been grown under hydrothermal conditions. The compound crystallizes in the ordered hydrocerussite [(PbCO(3))(2).Pb(OH)(2)] structure and can be derived from a close packing of the metal atoms with a stacking sequence of [c(h)(2)](3) along the c axis. O and F atoms are situated approximately in the tetrahedral voids, resulting in the formation of a slightly distorted [BaF(6)O(6)] icosahedron and a [1+6+3]-coordinate Pb atom, with one short bond to F, six bonds to O and three longer bonds to additional O atoms. The carbonate group deviates only slightly from the geometry of an equilateral triangle.

Journal Article↗

PubMed2002

Hg(3)Se(3)O(10), a mercury(II) compound with mixed-valence oxoselenium(IV/VI) anions.

The title compound, trimercury(II) bis[selenite(IV)] selenate(VI), contains three crystallographically inequivalent HgII cations with coordination numbers of eight (denoted Hg1 and Hg2) and five (denoted Hg3). The corresponding coordination polyhedra around the metal atoms might be described as intermediates between a square antiprism and a triangulated dodecahedron for both Hg1 and Hg2, and a strongly distorted truncated octahedron for Hg3. (infinity)2[HgO(8/2)] layers of edge-sharing [HgO(8)] polyhedra propagate parallel to the bc plane, and are connected via SeVIO(4) tetrahedra and [Hg3O(5)] polyhedra along the a axis, forming an arrangement with channels propagating parallel to the b axis. The two independent SeIVO(3) pyramids bridge the Hg atoms, and the non-bonding orbitals of the SeIV ions protrude into the channels from opposite sides.

Journal Article↗

PubMed2002

Hg(3)AlF(6)O(2)H, a structure with a short interpolyhedral O...O distance.

The crystal structure of Hg(3)AlF(6)O(2)H, trimercury(II) aluminium hydrogen hexafluoride dioxide, can be derived from a slightly distorted cubic close-packed (ccp) arrangement of the metal atoms, where three quarters of the positions are occupied by Hg atoms and one quarter by Al atoms. The F and O atoms are considerably dislocated from the tetrahedral voids of this arrangement, thus forming [HgO(2)F(6)] polyhedra, with two short Hg-O distances, two intermediate Hg-F distances and four longer Hg-F distances, and nearly ideal [AlF(6)] octahedra. The H atoms are presumably located close to the inversion centre. Their positions were derived from crystal chemical arguments, and they take part in the formation of O-H.O hydrogen bonds between two O atoms, with an O.O distance of 2.562 (9) A.

Journal Article↗