Synthesis and crystal structure of Bi{sub 6.4}Pb{sub 0.6}P{sub 2}O{sub 15.2}

• Published in: Journal of solid state chemistry Vol. 180; no. 10
• Main Authors: Arumugam, N., Lynch, V., Steinfink, H.
• Format: Journal Article
• Language: English
• Published: United States 15.10.2007
• Subjects: BISMUTH COMPOUNDS; BOND LENGTHS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LAYERS; LEAD IONS; LEAD PHOSPHATES; MONOCLINIC LATTICES; MONOCRYSTALS; OXYGEN IONS; STOICHIOMETRY; SYNTHESIS; X-RAY DIFFRACTION
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2007.07.021

Bi{sub 6.4}Pb{sub 0.6}P{sub 2}O{sub 15.2} is a polymorph of structures with the general stoichiometry Bi{sub 6+x}M{sub 1-x}P{sub 2}O{sub 15+y}. However, unlike previously published structures that consist of layers formed by edge sharing OBi{sub 4} tetrahedra bridged by PO{sub 4} and TO{sub 6} (T=transition metal) tetrahedra and octahedra the title compound's structure is more complex. It is monoclinic, C2, a=19.4698(4) A, b=11.3692(3) A, c=16.3809(5) A, {beta}=101.167(1){sup o}, Z=10. Single-crystal X-ray diffraction data were refined by least squares on F{sup 2} converging to R{sub 1}=0.0387, wR{sub 2}=0.0836 for 7023 intensities. The crystal twins by mirror reflection across (001) as the twin plane and twin component 1 equals 0.74(1). Oxygen ions are in tetrahedral coordination to four metal ions and the O(BiPb){sub 4} units share corners to form layers that are part of the three-dimensional framework. Eight oxygen ions form a cube around the two crystallographically independent Pb ions. Pb-O bond lengths vary from 2.265(14) to 2.869(14) A. Pairs of such cubes share an edge to form a Pb{sub 3}O{sub 20} unit. The two oxygen ions from the unshared edges are part of irregular Bi polyhedra. Other oxygen ions of Bi polyhedra are part only of O(BiPb){sub 4} units, and some oxygen ions of the polyhedra are also part of PO{sub 4} tetrahedra. One, two, three and or four PO{sub 4} moieties are connected to the Bi polyhedra. Bi-O bond lengths {<=}3.1 A vary from 2.090(12) to 3.07(3) A. The articulations of Pb cubes, Bi polyhedra and PO{sub 4} tetrahedra link into the three-dimensional structure. - Graphical abstract: View of the structure of Bi{sub 6.4}Pb{sub 0.6}P{sub 2}O{sub 15.2} parallel to the b-axis.