New Borophosphates in Main Group element Al, Ga and In Systems : Syntheses and Structures

J.-T. Zhao,^a J.-X. Mi, ^b Y.-X. Huang,^bc M.-R. Li,^ac S.-Y. Mao^b and R. Kniep^c

^aState Key Laboratory of High Performance Ceramics and Superfine Structures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P.R. China; ^bCollege of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P.R. China; ^cMax-Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany (jtzhao@mail.sic.ac.cn)

Borophosphates, as potential microporous materials, have drawn much attention in recent years and shown rich structural chemistry[1]. Although many compounds with transition metal elements have been reported, compounds with the p-block main group elements participating in the framework are rare. During our systematic investigations of borophosphate compounds in systems containing Al, Ga and In elements, more than ten new phases have been synthesized by mild hydrothermal methods and structurally characterized by X-ray diffraction methods [2].

Although the molar ratio of the main non-oxygen elements (or cations), A^I : M^III : B : P, are all the same in different compounds, they form four different structures belonging to four types. The preferences of the type seem largely governed by the ratio of the cation sizes of A^I and M^III. These four structure types contain different anion complex of borophosphates. These different anion complexes have different connectivity to the octahedral M^IIIO₆ units, which lead to different porosities in these structures. A^I cations reside inside the channels with 6- or 8-membered rings of polyhedral units as cross sections.

A^IM^III[BP₂O₇(OH)₃] , A^I = Na, K; M^III = Ga, In; monoclinic, C2/c, NaFe[BP2O7(OH)3] type [3]. The structure contain isolated anion units [(OH)O₂PO_1/2-O_1/2B(OH)₂O_1/2-O_1/2PO₃]^4-.

NaIn[BP₂O₈(OH)] [4], triclinic, P-1, new type. The structure contains dimeric [O_1/2O₃P-B(OH)O_3/2-O_2/2PO₂]^4- units.

A^IIn[BP₂O₈(OH)] , A^I = K, NH₄, Rb; triclinic, P-1, KFe[BP2O8(OH)] type [3]. The structures also contain dimeric [O_1/2O₃P-B(OH)O_3/2-O_2/2PO₂]^4- units. It is an intergrowth structure with the above type.

A^IM^III[BP₂O₈(OH)] , A^I = NH₄, Rb, Cs; M^III = Al, Ga; monoclinic, P2₁/c, RbFe[BP2O8(OH)] type [5]. The structures contain connected [O₂PO_2/2-O_3/2B(OH)-O_1/2PO₃]^4- units.

References

1 Kniep, R., Engelhardt, H. and Hauf, C. (1998) Chem. Mater. 10, 2930-2934.

2 Zhao, J.-T., Mi, J.-X., Huang, Y.-X., Li, M.-R., Mao, S.-Y., Kniep, R. et al. (2001) Z. Kristallogr. NCS 216, 15-16; (2002) Z. Kristallogr. NCS 217, 3-8; 163-172; 305-306.

3 Boy, I., Cordier, G., Eisenmann, B. and Kniep, R. (1998) Z. Naturforsch. 53B, 165-170.

4 Li, M.R., Master Thesis, Xiamen University, (2002), p.60.

5 Kniep, R., Boy, I. and Engelhardt, H. (1999) Z. Anorg. Allg. Chem. 625, 1512-1516.