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1997 (2)
1994 (1)
1Author    Prof, Dr, DrRequires cookie*
 Title    Aluminiumphosphate mit nichtzentrosymmetrischen Schicht-und Raumnetzstrukturen aus topologisch verwandten Motiven: 2. KA12(P 0 4 )2 (0 H )* 2 H 20  
 Abstract    Alum inum Phosphates w ith N on-C entrosym m etric Layer-and Fram ew ork-Structures o f Topologically R elated M otifs: 2. K A l2(P0 4)2(0 H)-2 H 20 Stefan D icka, Gisbert G roßm annb, G isela O hm sb, M anfred M üller0 KAl2(P04)2(0 H)-2H20 was obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 373 K. A single crystal X-ray structure analysis showed that it is an ordered, F-free K-analog of the microporous compound AIPO4-CI2 . Crystal data: orthorhombic space group P 2 \2 \2 \, a = 920.5(1), b = 970.7(2), c = 982.8(2) pm, Z -4. The structure consists of dimeric units of AIOö octahedra and AIO5 trigonal bipyramids, bridged by an OH and two bidentate phosphate groups. The dimers are linked by phosphate to form corrugated layers which are topologically related to the layers in KAl2(P04)2(0 H)-4H20 and minyulite. The layers are connected by Al-O-P and hydrogen bonds to a three dimensional framework structure with K ions in channel-like cavities. A neutron powder scattering experiment with KAb(P04)2(0 D)-2D20 showed that the bridging OD group and only one D of each water molecule are involved in hydrogen bonding. 31P MAS NMR spectra show two isotropic lines at 6iso = —6.9 and -18,7 ppm of the intensity ratio 1:1 and confirm the presence of two crystallographically independent P atoms in the unit cell. In the 'H MAS NMR spectra the water molecules and the bridging OH group show signals at 5.9 and 1.1 ppm, respectively. 
  Reference    Z. Naturforsch. 52b, 1447—1455 (1997); eingegangen am 9. September 1997 
  Published    1997 
  Keywords    Crystal Structure, Neutron Scattering, MAS NMR, Aluminium Phosphate 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-1447.pdf 
 Identifier    ZNB-1997-52b-1447 
 Volume    52 
2Author    StefanD. Icka, Gisbert Großmannb, G. Isela, Ohm Sb, Thom As ZeiskecRequires cookie*
 Title    Aluminiumphosphate mit nichtzentrosymmetrischen Schicht-und Raumnetzstrukturen aus topologisch verwandten Motiven: 1. KA12(P 0 4)2(0H)*4H20 Aluminum Phosphates with Non-Centrosym metric Layer-and Framework-Structures o f Topologically Related Motifs  
 Abstract    KAl2(P04)2(0 H)-4H20 could be obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 333 K. A single crystal X-ray structure analysis showed that KAl2(P04)2(0 H)-4H20 is isotypic with the mineral minyulite. Crystal data: orthorhombic space group P b a l, a = 934.7(1), b = 982, 1 (1), c = 551,0(1) pm, Z = 2. It possesses dimeric units of Al-octahedra which are bridged by an OH-and two bidentate phosphate groups. The dimers are linked by phosphate to plane polar layers. Cavities in the layers are occupied by K ions. One corner of each phosphate tetrahedron is not connected to Al but accepts four hydrogen bonds from water molecules bound to Al of the adjacent layer. A powder neutron scattering experiment with KAl2(P04)2(0 D)-4D20 showed that four D atoms and P coordinate the hydrogen bond accepting O in KAl2(P04)2(0 D)-4D20 like a square pyramid. Analogous dimeric building units are found in the Al phosphate minerals minyulite and morinite; similar dimers of Fe octahedra occur in the mineral copiapite, a number of Fe containing enzymes and numerous synthetic iron complexes. High-resolution 31P solid-state NMR spectra show only one isotropic line at <5;so = —9.6 ppm and confirm the presence of one symmetry independent phosphorus site in the unit cell. In the 'H-MAS-NMR spectra the water molecules and the bridging OH groups show signals at 5.4 and 1.4 ppm, respectively. 
  Reference    Z. Naturforsch. 52b, 1439—1446 (1997); eingegangen am 9. September 1997 
  Published    1997 
  Keywords    Crystal Structure, Neutron Scattering, MAS NMR, Minyulite, Aluminium Phosphate 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-1439.pdf 
 Identifier    ZNB-1997-52b-1439 
 Volume    52 
3Author    J.-Ch Buhl, C. Mundus, J. Löns, W. HoffmannRequires cookie*
 Title    On the Enclathration of N aB(O H )4 in the /J-Cages of Sodalite: Crystallization Kinetics and Crystal Structure  
 Abstract    The hydrothermal formation of sodium hydroxyborate enclathrated sodalite synthesized from an initial ternary mixture of mullite, cristobalite and corundum has been investigated. Depending on temperature and pressure the compound Na7-5[AlSi04]6[B(0H)4]1.5 • 2 H 20 could be synthesized in form of polycrystalline powder as well as in form of single crystals. The kinetics of the sodalite growth could be determined at 423 K and 473 K. 29Si-and 27A1 MAS NMR was shown to be the preferred method to describe the conversion into sodalite quantitatively. Evidence for the first formation of polycrystalline sodalite has been found after the total dissolution of mullite and cristobalite. Single crystal X-ray diffraction data were used for the structure determination and refinement. The position and orientation of the hydroxyborate anions within the sodalite's /J-cages could only be found in the course of a "rigid body" refinement with constraints for the B(OH)4 tetrahedron. The boron atoms are located in an off-centre position within the sodalite cages. One out of the four oxygen atoms of the hydroxyborate group is positioned near the centre of a face of the sodium tetrahedron, whereas the three remaining oxygen atoms are near to the middle of its edges. 
  Reference    Z. Naturforsch. 49a, 1171—1178 (1994); received September 26 1994 
  Published    1994 
  Keywords    Sodalite solid solution, Crystallization kinetics, IR-spectroscopy, MAS NMR, Structure refinement 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-1171.pdf 
 Identifier    ZNA-1994-49a-1171 
 Volume    49