Structural Chemistry of Borophosphates, Metalloborophosphates, and Related Compounds

Abstract

A concept for the classification of crystalline (metallo)borophosphates in terms of structural chemistry is proposed and the compounds known to date are classified in an overview. Similarities and differences with (alumo)silicates and Liebau's classification are discussed with respect to the observation that the different borate and phosphate complexes are not interconnected arbitrarily in borophosphates. By combination and extension of existing concepts for silicates and borates a hierarchical system based on oligomeric building units has been developed. The observed connection rules are rationalized and the strong influence of the composition on dimensionality and structural motifs of the formed anions is pointed out. Likewise the effect of OH groups is taken into account by grading anions according to the degree of protonation (ratio O:OH). A general distinction is made between tetrahedral and mixed coordinated borophosphates. Metalloborophosphates are treated separately as special cases of borophosphates. Finally, anion‐substituted compounds, border cases, and borate‐phosphates complete the overview.

Novel Fundamental Building Blocks and Site Dependent Isomorphism in the First Actinide Borophosphates

“…The B/P ratio is 1:2, and the topology of the unit can be represented as a derivative of the simplest 3□:3□ FBB. 2 36 Each FBB has a descriptor of the form A:B, where A gives the number of borate triangles (Δ) and tetrahedra (□) in the FBB in the form iΔj□, where i and j are the numbers of triangles and tetrahedra, respectively. The delimiters, ⟨ ⟩ and [ ], are used to identify the rings of polyhedral and connected anions, polyhedra, or rings.…”

“…2 The topology of the layers (in the case of AgNBPU-2,3 it is a quasilayer fragment) can be described with an anion topology method. 38 The black and white graphs for both structures are presented in Figure 4.…”

Silver(I) diaquanickel(II)catena-borodiphosphate(V) hydrate, (Ag0.57Ni0.22)Ni(H2O)2[BP2O8]·0.67H2O

“…For other borophosphates, see: Kniep et al (1998); Ewald et al (2007); Lin et al (2008). For bond valence calculations see: Brown & Altermatt (1985).…”

Determination of the Hydrogen Positions in the Novel Barium Boroarsenate Ba[B2As2O8(OH)2] by Combined Single Crystal X‐ray and Powder Neutron Investigations

“…tetraoxoborate [BO 4 ] 5-together with other units as for example phosphate [PO 4 ] 3-, which in turn generates a large diversity of new structures. [1] Borate groups in combination with group 15 oxotetrahedra, such as PO 4 , can produce building-blocks isoelectronic with silicates and lead to analogous structures, such as the quartz heterotype BPO 4 , [2] but also chain structures or threedimensional frameworks. [3,4] This analogy also holds for the combination of borate groups with arsenate groups, [AsO 4 ] 3-, where detailed investigations have recently started.…”