Tetrahedral networks containing beryllium: Syntheses and structures of Be-3(PO4)2 center dot 2H(2)O and Be(HAsO4)center dot H2O

The hydrothermal syntheses and single crystal structures of Be-3(PO4)(2). 2 H(2)O and Be(HAsO4). H2O are described. These phases are built up from vert ex-sharing tetrahedra, but their overall structures are quite different. In Be-3(PO4)(2). 2H(2)O, BeO4, BeO2(H2O)(2), and PO4 groups build up a three- dimensional structure via Be-O-P and Be-O-Be bonds, resulting in tetrahedra l 3- and 4-rings. Be(HAsO4). H2O is layered and contains 6-rings of BeO3(H2 O) and HAsO4 building blocks fused via Be-O-As bonds. Similarities and diff erences to some other tetrahedral structures are discussed. Crystal data: B e-3(PO4)(2). 2H(2)O, M-r = 253.01, monoclinic, space group C2/c (No. 15), a = 15.9640 (6) Angstrom, b = 4.5842(2) Angstrom, c = 95320(1) Angstrom, bet a = 94.366(2)degrees, V = 695.6(2) Angstrom(3), Z = 4, R(F) = 3.79%, R-w(F) = 4.44% [812 reflections with I > 2 sigma(I)]. Be(HAsO4). H2O, M-r = 166.9 5, orthorhombic, space group Pca2(1) (No, 29), a = 9.7471(2) Angstrom, b = 4.6794(1) Angstrom, c = 8.5929(1) Angstrom, V = 391.93(9) Angstrom(3), Z = 4, R(F) = 3.93%, R-w(F) = 4.32% [795 reflections with I > 2 sigma(I)]. (C) 1999 Academic Press.