Kurze O-O-Abstände einer gemeinsamen Polyederkante bei Verknüpfung von PO4-Tetraedern mit VO6-Oktaedern im Vanadyl-Orthophosphat CaNi(VO)(PO4)2 / Short O-O Distances in Edge Sharing PO4 Tetrahedra and VO6 Octahedra of the Vanadyl- Orthophosphate CaNi(VO)(PO4)2

Single crystals of the new compound CaNi(VO)(PO4)2 have been prepared by solid state reactions below the melting point of the oxide mixture in evacuated quartz tubes. X-ray investigations led to orthorhombic symmetry, space group D2h16-Pnma, a =14.113(1), b =6.408(1), c = 7.364(1) Å, Z = 4. The crystal structure shows 1∞[NiO4] and 1∞[VO6P2O3] polyhedra chains closely related to analogous chains in the isotypic compound CdV2O(PO4)2. The short V -O distance of 1.66 Å indicates a vanadyl group as the main difference to CdV2O(PO4)2. The short O-O distance of 2,395 Å of the edge-sharing PO4 tetrahedra and VO6 octahedra is discussed.

Kantenverknüpfte VO6-0ktaeder und PO4-Tetraeder in BaCa(VO)(PO4)2 / Edge-Connected VO6 Octahedra and PO4 Tetrahedra in BaCa(VO)(PO4)2

Single crystals of the new compound BaCa(VO)(PO4)2 have been prepared by solid state reactions below the melting point of the reactants in evacuated quartz tubes. X-ray investigations led to monoclinic symmetry, space group C2h5 - P21/c, a = 7.300(1), b = 7.053(1), c = 14.460(1) Å, β = 101,43(1)°, Z = 4. The crystal structure is characterized by layers of corner-and edge-connected PO4 tetrahedra and VO1+5 octahedra. There is an unusually short O(1)-O(4) distance in a VO6 octahedron of 2.44 Å associated with the sharing of edges with PO4 tetrahedra. The short V-O distance of 1.61 Å indicates a vanadyl group.

Synthese und Röntgen-Strukturuntersuchung von Rb4Cd(VO)(V2O7)2Cl und Tl4Cd(VO)(V2O7)2Cl / Synthesis and X-Ray Structure Analysis of Rb4Cd(VO)(V2O7)2Cl und Tl4Cd(VO)(V2O7)2Cl

Single crystals of (I) Rb4Cd(VO)(V2O7)2Cl und Tl4Cd(VO)(V2O7)2Cl have been prepared by flux techniques. The compounds were examined by X-ray analysis. They crystallize with tetragonal symmetry, space group C14-P4 with (I): a=9.142(1); c=5.525(1), (II): a=9.150(1), c=5.405(1) A, Z = 4. Both compound belong to the K4CuV5O15Cl-Type. V (l) forms V2O7 double tetrahedra, connected by square V(2)O5 pyramids and CdO4Cl2 octahedra. The short V(2)-O distance indicates a vanadyl group.

Synthese und Struktureines Strontium-Vanadyl-Phosphats: Sr2(VO)(PO4)2 / Synthesis and Structure of a Strontium Vanadyl Phosphate: Sr2(VO)(PO4)2

Dark green single crystals of Sr2(VO)P2O8 have been prepared by solid state reactions in closed quartz tubes. X-ray investigations led to monoclinic symmetry, space group C2h6-I2/a, a = 6.744(4), b = 15.866(4), c = 7.032(2) Å, β = 115.41(2), Z = 4. Sr2(VO)P2O8 is isotypic to Sr2(VO)V2O8 and shows V4+ in split positions. The split positions are in non-centric octahedral coordination forming a short vanadium to oxygen distance typical for the vanadyl group. The crystal chemistry of the monovanadyl orthophate Sr2(VO)P2O8 is discussed considering related divanadyl phosphates.