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1997 (1)
1Author    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