Karsten Bluhm

Über CuDy2[B8O16] und CuHo2[B8O16]: Zwei neue „Metaborate“ mit einem ∞1[B8O16]8--Anion / On CuDy2[B8O16] and CuHo2[B8O16] Two New „Metaborates“ with a ∞1[B8O16]8-Anion

Nearly colourless single crystals of the compounds CuDy2[B8O16] (I) and CuHo2[B8O16] (II) have been obtained by a B2O3 flux technique. They crystallize in the structure of CuTb2[B8O16] (I) or in an orthorhombic variant (II). X-ray investigations on single crystals led to the space group C2h5 - P21/c (Nr. 14) with lattice parameters a = 1025,5(10); b = 836,99(10); c = 621,2(8) pm, β = 90.47(10)°; Z = 2 (I) and D2h9 - Pbam (Nr. 55) with a = 840,7(2), b = 616,6(2), c = 1022,0(2) pm, Z = 2 (II). The structures contain 1∞[B8O16]8- chains isolated from each other, which include tri- and tetracoordinated boron. The chains consist of alternating twelve and eight-membered rings of boron and oxygen atoms connected by BO4 units. Dy3+ and Ho3+ are octacoordinated and Cu2+ is hexacoordinated in elongated octahedra by oxygen. The relation between these two structures is discussed.

Zur Synthese und Kristallstruktur von Bariumboroarsenat Ba(BAsO5) mit einem Beitrag über Bariumorthoarsenat Ba3(AsO4)2 / Synthesis and Crystal Structure of Barium Boroarsenate Ba(BAsO5) with a Contribution on Barium Orthoarsenate Ba3(AsO4)2

Single crystals of Ba(BAsO5) (I) and Ba3(AsO4)2 (II) were obtained by melting B2O3, arsenic pentoxide and BaO at 1100°C. Both compounds crystallize trigonally, space groups (I): C32 - P31 (Nr. 144), (II): D3d5 - R3̄m (Nr. 166), with the lattice parameters (I): a = 726.7(1), c = 710.6(1) pm, Z = 3 and (II): a = 576.7(1), c = 2116.3(2) pm, Z = 3. Ba(BAsO5) is isotypic to Pb(BAsO5) (Stillwellite structure) and Ba3(AsO4)2 to Ba3(PO4)2. The structure of Ba(BAsO5) is characterized by helical chains of rings of two borate tetrahedra and one arsenate tetrahedron. Barium is tenfold coordinated by oxygen. A rod-like sequence of coordination polyhedra, AsO4- Ba(2)O10-Ba(1)O12-Ba(2)O10-AsO4 is characteristic in the crystal structure of Ba3(AsO4)2.

Synthese und Kristallstruktur von Dibariumzink-bis(cyclotriborat) Ba2Zn(B3O6)2/Synthesis and Crystal Structure of Di-barium Zinc Bis-cyclotriborate Ba2Zn(B3O6)2

Abstract Single crystals of the new compound Ba2Zn(B3O6)2 were obtained by using a B2O3 flux technique. They crystallize in an as yet unknown structure type. X-ray investigations led to space group Ci1-P1̄ (Nr.2) with lattice parameters a = 715.5(2), b = 720.5(2), c = 1178.9(4), a = 78.96(2)°, β = 85.45(2)°, γ = 60.12(1)°, Z = 2. The structure is characterized by isolated (B3O6)3--rings and contains two ninefold coordinated Ba-sites. Zn2+ is tetrahedrally coordinated by oxygen. The relation to the crystal structures of high-temperature BaB2O4 and Ba2Ca(B3O6)2 is discussed.

Zur Synthese und Kristallstruktur von Zinkboratoxiden mit isolierten, trigonal planaren BO3-Baugruppen: Zn5Mn(BO3)2O4 und ZnFe(BO3)O / Synthesis and Crystal Structure of Zinc Borate Oxides Containing Isolated Trigonal Planar BO3 Units: Zn5Mn(BO3)2O4 and ZnFe(BO3)O

Single crystals of the new compounds Zn5Mn(BO3)2O4 (A ) and ZnFe(BO3)O (B) were prepared by using a B2O3 flux technique. Zn5Mn(BO3)2O4 is isostructural with Ni5Ti(BO3)2O4 and ZnFe(BO3)O is isotypic with the mineral warwickite. X-ray investigations on single crystals led to (A ) space group D92h -Pbam, a = 926.41(10), b = 1236.67(8), c = 304.55(3) pm, Z = 2, and (B) space group D162h-Pnma, a = 924.62(4), b = 314.1(10), c = 935.3(2) pm, Z = 4. The structure of Zn5Mn(BO3)2O4 (A ) contains four octahedrally coordinated metal sites, one of these statistically occupied by Zn2+ and Mn4+. In the structure of ZnFe(BO3)O the ions Zn2+ and Fe3+ occupy statistically both distorted octahedral sites. Both structures contain isolated BO3 units and oxygen that is not coordinated to boron.

Synthese und Kristallstruktur von manganhaltigen Pyroboraten: MnCo(B2O5) und MnMg(B2O5) / Synthesis and Crystal Structure of Manganese Containing Pyroborates: MnCo(B2O5) and MnMg(B2O5)

The compounds MnCo(B2O5) (I) and MnMg(B2O5) (II) were prepared by using B2O3 flux techniques in an argon atmosphere. X-ray investigations on single crystals showed triclinic symmetry, space group Ci1 - P1̄, I: a = 320.94(10), b = 619.20(11), c = 939.0(2) pm, a = 104.38(2)°, β = 90.76(2)°, γ = 92.046(14)° and II: a = 318.97(7), b = 619.8(2), c = 936.7(2) pm, α = 104.47(2)°, β = 90.60(2)°, γ = 91.98(2)° Z = 2. Their structures are isotypic with Co2(B2O5). All metal ions are octahedrally coordinated by six oxygen atoms. The structures contain diborate anions B2O54-. Each boron atom is threefold coordinated by oxygen.

Synthese und Kristallstruktur von Lanthanoidzinkboraten LnZn(B5O10) mit Ln = Ce, Nd, Tb / Synthesis and Crystal Structure of Rare Earth Zinc Borates LnZn(B5O10) with Ln = Ce, Nd, Tb

Single crystals of the new compounds LnZn(B5O10) (Ln = (A) Ce3+, (B) Nd3+, (C) T b3+) were obtained by using a B2O3 flux technique. X-ray investigations led to space group C2h5-P21/n (Nr. 14) with lattice parameters: (A) a = 874.5(1), b = 761.4(1), c = 950.0(1), β = 92.80(1)°, (B) a = 868.6(2), b = 760.9(2), c = 946.0(2), β = 92.99(2)°, (C) a = 858.2(2), b = 760.5(2), c = 939.3(2), β = 93.56(2)°, Z = 4. The structure is isotypic with CoSm(B5O10) and is characterized by two-dimensional infinite 2∞ (B5O 10)5- ions. Ln is tenfold coordinated by oxygen, and Zn2+ occupies distorted ZnO6 polyhedra.

Synthese und röntgenographische Charakterisierung von zwei neuen Verbindungen des Ludwigit-Strukturtyps: Co5Sn(BO3)2O4 und Co5Mn(BO3 )2O4/Synthesis and X -Ray Characterization of Two New Compounds with Ludwigite-Structure: Co5Sn(BO3)2O4 and Co5Mn(BO3)2O4

Abstract The compounds Co5Sn(BO3)2O4 (I) and Co5Mn(BO3)2O4 (II) were prepared by using a B2O3 flux technique. Single crystals were investigated by X-ray diffraction and showed orthorhombic symmetry, space group D2h9-Pbam (No. 55), I a = 944.4; b = 1233.8; c = 310.5 pm; Z = 2 and II a = 925.07; b = 1241.67; c = 305.24 pm; Z = 2. Both compounds are isotypic to the mineral Ludwigite. All metal point positions show an octahedral oxygen coordination. Co2+ and M4+ (M = Sn or Mn) occupy one point position statistically. Both structures contain isolated, trigonal planar BO3 units and oxygen atoms that are not coordinated to boron.

Zur Synthese und Kristallstruktur von manganhaltigen Boratoxiden: MnFe(BO3)O und MnAl0,5Yo,5(BO3)O / Synthesis and Crystal Structure of Manganese Borate Oxides: MnFe(BO3)O and MnAl0,5Yo,5(BO3)O

Single crystals of the compounds MnFe(BO3)O (I) and MnAl0.5Y0.5(BO3)O (II), were obtained by a B2O3 flux technique. I crystallizes with orthorhombic symmetry, space group D162h -Pnma (Nr.62), a = 939.92; b = 319.41; c = 939.11 pm; Z = 4 and II with monoclinic symmetry, space group C52h-P21/n (Nr. 14). a = 325.6; b = 955.1; c = 929.2 pm; β = 90.70° ; Z = 4. I is isotypic to the mineral Warwickite, while II is a distorded variant of this structure. All metal ions are octahedrally coordinated. Both structures contain isolated, trigonal planar BO3 units and oxygen atoms that are not coordinated to boron.

Synthese und Kristallstruktur von Verbindungen des Typs CuM[B5O10] (M = Tm3+, Lu3+) / Synthesis and Crystal Structure of Compounds of the Type CuM[B5O10] (M = Tm3+, Lu3+)

Abstract Single crystals of the compounds CuM[B5O10] (M = Tm3+(I), Lu3+(II) have been obtained by a B2O3 flux technique. Their structures are isotypic with CuTb[B5O10]. X-ray investigations on single crystals led to the space group C212v-Iba2 (Nr. 45); I: a = 622,0(2) pm; b = 844,7(1) pm; c = 1266,3(4) pm; Z = 4 and II: a = 618.4(1) pm; b = 845,9(2) pm; c = 1260,9(4) pm; Z = 4. The structure contains 1∞[B5O10]5- chains that include twelve membered rings of boron and oxygen. Each ring consists of two tetrahedral BO4 and two planar B2O5 groups and is connected with neighboring rings via the BO4 units. M3+ (M = Tm3+, Lu3+) is eight-coordinated, while Cu2+ is hexa-coordinated by oxygen.

Synthese und Kristallstruktur von NiHo2(B2O5)2, das erste Nickellanthanoidborat mit einem 2∞(B2O5)4- -Anion / Synthesis and Crystal Structure of NiHo2(B2O5)2, the First Nickel Lanthanoid Borates with a (B2O5)4- Anion

Single crystals of NiHo2(B2O5)2 were prepared by a B2O3 flux-technique in high temperature reactions at 1450 °C and investigated by X-ray diffraction. They crystallize in the space group C2h5-P21/c (Nr. 14) with a = 451.0(4); b = 724.8(3); c = 938.8(6) pm; β = 91,39( 1)°; Z = 2. The compound is isotypic to CuTb2 (B2O5)2 as well as to the gadolinite structure (FeY2(BeSiO5)2) and contains a two dimensional infinite anion with the formula 2∞ (B2O5)4-. The borate layers consist of four- and eight-membered rings of edge-sharing BO4 tetrahedra. The layers are connected via copper-centered elongated oxygen-octahedra and slightly distorted tetragonal HoO8 antiprisms.