Oligomere Tetraeder-Anionen in Borophosphaten: Darstellung und Kristall­strukturen von NaFe[BP2O7(OH)3] und K2Fe2[B2P4O16(OH)2 ]/Oligomeric Tetrahedral Anions in Borophosphates: Synthesis and Crystal Structures of NaFe[BP2O7(OH)3] and K2Fe2[B2P4O16(OH)2]

Abstract

Abstract Crystals of the title compounds were grown under hydrothermal conditions. The crystal structures were determined by single crystal data. NaFe[BP2O7(OH)3] (monoclinic, C 2/c, a = 1042.0(2), b = 821.5(1), c = 921.7(1) pm, β = 116.60(1)°, Z=4): The crystal structure contains isolated anions [BP2O7(OH)3]4-, which correspond to trinuclear units PO1/2O3-BO2/2(OH)2 -PO1/2O2(OH) of corner sharing tetrahedra. Fe3+ is coordinated octahedrally by oxygen, Na+ is 8 -fold coordinated by oxygen forming cubes. K2Fe2[B2P4O16(OH)2] (triclinic, P1̄, a = 516.7(1), b = 808.9(1), c = 834.0(1) pm, α = 87.06(f), β = 80.21(1), γ = 86.59(1)°, Z = 1): The crystal structure contains isolated anions [B2P4O16(OH)2]8-. Four-membered rings of tetrahedra with two additional terminal phosphate groups are formed by condensation of two trinuclear units P O1/2O3 -BO3/2(OH) -PO2/2O2. Fe3+ is in an octahedral and K+ in an irregularly 10-fold coordination by oxygen.