B3DyO6, orthorhombic, Pnma (no. 62), a = 15.9431(9) A, b = 7.4036(4) A, c = 12.2618(7) A, V = 1447.3 A, Z = 16, Rgt(F) = 0.026, wRref(F) = 0.053, T = 293 K. Source of material Single crystals of -Dy(BO2)3 have been obtained by the reaction of Dy2O3 and B2O3 in the stoichiometric ratio 1 : 3 with a slight excess of fluxing DyCl3 in gas tightly sealed platinum crucibles within three weeks at 900 °C. The compound appears as colourless, thin, airand water-resistant needles which tend to severe growth-twinning due to their fibrous habit. Discussion In the range of the lanthanidemeta-oxoboratesM(BO2)3 (M = La Lu) there are meanwhile four modifications known of which three are realized for the light representatives. The -type compounds could be obtained under normal-pressure hightemperature conditions for M = La Nd, Sm Tb and crystallize monoclinically with space group I2/a (C2/c), e.g. [1]. Two highpressure high-temperature modifications were recently synthesized: the orthorhombic -M(BO2)3-type (M = La – Nd, Pca21) [2] and the monoclinic -La(BO2)3-type compounds (P21/c) [3]. For the first time, an example of the fourth known phase ofmetaoxoborates, -Tb(BO2)3 was obtained under normal-pressure high-temperature conditions [4], whereas single crystals of M(BO2)3 with M = Dy Lu [5] were accessible under highpressure high-temperature conditions exclusively. Only the here presented compound can be additionally synthesized under normal pressure. In the crystal structure, vertex-linked [BO4] tetrahedra [d(B—O) = 143 – 153 pm] are connected to strongly corrugated oxoborate layers running parallel to (100). Between these layers the four crystallographically independent Dy cations are located, each surrounded by eight oxide anions [d(Dy—O) = 226 – 283 pm]. Z. Kristallogr. NCS 223 (2008) 177-178 / DOI 10.1524/ncrs.2008.0073 177 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colourless needle, size 0.02 × 0.04 × 0.09 mm Wavelength: Mo K radiation (0.71069 A) : 205.78 cm−1 Diffractometer: Bruker-Nonius -CCD 2 max: 54.96° N(hkl)measured, N(hkl)unique: 18898, 1789 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 1680 N(param)refined: 197 Programs: SHELXS-97 [6], SHELXL-97 [7], DIAMOND [8] Table 1. Data collection and handling.