Crystal structure of the new borate Li3Gd(BO3)(2). Comparison with the homologous Na(3)Ln(BO3)(2) (Ln : La, Nd) compounds

The structure of Li3Gd(BO3)(2) has been solved by X-ray diffraction study o n single crystal. This novel berate crystallizes in the monoclinic system w ith the P2(1)/c space group (Z = 4). The cell parameters are respectively e qual to a = 8.724(2), b = 6.425(2), c = 10.095(2) Angstrom and beta = 116.8 5(2)degrees. Refinements of 110 parameters using 2924 independent reflectio ns having I > 2 sigma (I) converged to R-1 = 0.028 (omegaR(2) = 0.058). The structure of Li-3 Gd(BO3)(2) is made up of double layers of eightfold coor dinated Gd atoms parallel to the (bc) plane. They are linked by respectivel y three- and four-coordinated boron and lithium atoms. The structure is com pared to that of the homologous sodium compounds, Na(3)Ln(BO3)(2) (Ln: La, Nd), in which LnO(8) polyhedra also form a bi-dimensional array. (C) 2001 E ditions scientifiques et medicales Elsevier SAS. All rights reserved.