Crystallographic data for NiSeO4 • 6H2O and MgSeO4 • 6H2O

NiSeO« • 6H2O is tetragonal, probable space group D\—Pij2.fi, with a = 6.914, c = 18.420 Ä. MgSeO« • 6HjO is monoclinic, space group Cj^—C2/c, with a = 10.21, h = 7.35, c = 24.8 Ä and ß = 98°26'. Introduction The crystal properties of NiSeO^ • 6 H , 0 and MgSeO^ • öH^O have only been superficially investigated. Hopkin and Williams fine-grade NiSe04 • 6H2O and MgSe04 • 6H2O were used for this investigation. The x-ray powder-dilfraction patterns were obtained at 25°C in a Philips dilfractometer, using filtered CoKoi radiation {X = 1.7889 Ä). N i S e 0 4 6 H , 0 The tetragonal crystals are isomorphous with* NiS04 • ßH^O and have axial ratio^ a:c = 1:1.8364 = 1:2.596 • cos45°. The assignment of the peaks was made by analogy to the similar pattem of tetragonal NiS04 • 6H2O. All the observed peaks were satisfactorily ' H . E . SwANSON, N . T . GILFRICH a n d M. I . COOK, S t a n d a r d x r a y d i f f raction powder pat tems. National Bureau of StEindards Circular 539, 7 (1957) 36-37 . ^ J . W. ~ • ELLOR, A comprehensive treatise on inorganic and theoretical chemistry. 5th edition. Vol. 10. London, Longmans, Green and Co. Z. KristaUogr. Bd. 119, 5/6 3 0 466 Kurze Originalmitteilungon assigned as being due to a tetragonal lattice with the following unit-cell dimensions, determined by means of a least-square treatment: a = 6.914 ± 0.004 Ä, c = 18.420 ± 0.008 Ä. The axial ratio for NiSe04 • 6H2O is a\c = 1:2.664, which agrees well with the goniometric value. The calculated density at 25°C, assuming 4 molecules per unit cell, is 2.336 g/cm®, which is in agreement with the pycnometric value^ of 2.314 g/cm®. The observed spacings, assigned indices and observed relative intensities are listed in Table 1. The observed and the calculated spacings are in agreement within the limits of error of the lattice constants. Table 1. Pmcdtr data /or XiSeO, • 6H,0 • (CoKx radiation) h k 1 I k k 1 I k k 1 ' . k . k k 1 k k 1 Tat t 1 1 1 1 2 2 . > t 0 I 0 1 7 8 1 . 9 7 6 1 5 t 5 1 . 6 5 0 <:;:> / 2 t 5 » . « 0 5 0 0 « 100 2 . » 6 2 2 0 5 1 . 9 4 2 1 0 9 2 I . t 9 5 [ . 1 1 2 » . 3 M 1 1 2 U 2 . M 5 2 2 1 2 1 . 9 1 4 2 0 « ^ 5 5 1 1 5 9 5 . 8 2 7 1 1 5 8 2 . 5 « 9 1 2 5 8 • 2 5 0 ' 1 . 6 2 5 0 2 1 0 * ' S 5 5 5 . » » 0 2 0 1 8 2 . 5 1 8 1 1 7 5 1 . 9 1 5 2 2 6 1 6 P 0 1 1 1 i . t t s t 0 7 5 . 5 5 7 0 2 1 1 2 2 . 5 0 1 0 0 8 55 1 . 9 0 8 2 5 1 8 2 3 6 l . t 3 9 5 0 1 0 5 . S 5 1 0 l 5 t • 2 . 2 5 t 0 5 2 5 1 . 8 8 0 1 5 5 8 1 . 6 1 8 <::> I t l . t 2 6 2 t 5 5 . 2 5 7 0 2 2 8 2 . 1 8 5 0 1 8 1 . 8 7 8 2 5 2 4 • l . t 0 9 1 5 1 0 5 . 0 9 5 1 3 0 6 2 . 1 7 2 1 5 1 1 . 8 t 4 1 2 8 1 1 . 6 0 5 5 5 2 t i . t o t 0 2 1 2 3 . 0 5 0 1 2 1 5 2 . 1 5 9 2 2 t 1 8 , 1 5 6 1 . 5 7 6 <;;> l . t o o 2 5 9 5 . 0 1 5 0 2 5 20 2 . 1 2 8 1 5 2 2 t 1 . 7 8 0 [0 1 1 0 ] 20 k * 1 . 5 8 5 5 0 0 a . » » 2 1 1 5 2 . 0 9 t 2 0 7 1 * 1 t 0 ' 1 . 5 6 5 0 1 5 8 1 . 5 5 6 1 t 8 2 . 9 5 5 1 2 2 t " 2 . 0 8 t 1 1 8 1 1 . 7 4 1 0 2 9 2 I . 5 t 6 2 t 0 2 I . 5 t 2 1 5 2 2 . B 0 6 0 t 6 2 2 . 0 6 1 , 1 5 5 0 5 t ' 1 . 7 2 2 0 t 1 2 t 1 . 5 t l 2 t 1 6 1 . 5 5 5 2 t 7 2 . 7 « 5 0 2 t 52 1 . 6 8 2 1 5 7 t ( " \ 1 . 5 5 0 5 5 8 2 . 6 0 0 1 1 6 52 2 . 0 5 8 2 2 5 2 1 . 6 7 6 2 2 8 1 2 1 . 5 5 t 0 0 1 2 6t k 2 . 5 4 » 1 2 t 5 2 .005 1 2 7 2 1 . 6 4 t 0 t 5 1 2 ^ 5 9 ' b b r M 4 ; p p v a r l r r * s « l T « 4 i • •h*«14«r The reflections appear to be limited to: 001 only with l = 4n. The space group of NiSe04 • 6H2O may be eitherDJ, or C\, depending on whether the reflections OäK) for k odd appear or not. However, since the space group for NiSe04 • 6H2O is D\ — P4j2i2, this may also be taken as the probable space group in the present case. MgSeOi 6 H 0 j The MgSe04 • 6H2O diffraction peaks were indexed by means of the dose similarity of its pattern to that of MgS04 • GHjO®. All the observed peaks could be satisfactorily explained as being due to a monoclinic lattice with the following unit-cell dimensions, as determined by a least-square treatment: a = 10.21 ± O.Ol Ä, 6 = 7.35 db O.Ol Ä. c = 24.79 ± 0.02 Ä, ß = 98°26' ± 3'. The axial ratios for MgSeO« • eH^O are a:b:c = 1.3896:1:3.3760 which agree well with the goniometric values^ of a:b:c = 1.3853:1: i (3.3700). The calculated density of MgSeOi • 6H2O at 25 °C, assuming Z = 8, is 1.989 g/cm®. The pycnometric density is 1.928 g/cm®. The observed spacings, assigned indices and observed relative intensities are listed in Table 2. K. H. IDE, ThestructureofMgSOi • öHjO. Naturwissensch. 26 (1938)411. Kurze Originalniitteilungen 467 Table 2. Potcder data IOT MuSeOt • 6 H,0 • (CoKx radiation) bhl I bkl I bhl I hkl • bk: l t . l t t 004 12 4.47 1 1» 100 5.4JO 1 20; S» 2.945 1 225 55 2.605 1 314 16 5.9* 5.»9 110 i n 4.21 202 204 1» 3.551 5.257 025 116 58 »0 2.873 9 b 2.562 2.547 119 »02 6 9 5.67 I I I 4.092 006 56 3.151 034 5 2.832 222 22 2.J24 »00 8 5.5» 112 56 5.950 115 S 5.060 510 27 2.810 208 12 2.475 317 5 5.17 112 55 5.67» 020 10 2.99« 515 13 2.769 224 2 2.463 208 5.0» 200 5.642 20» 17 2.975 206 50 2.734 026 10 <».4' S » . « 005 »7 5.511 I i i 17 '220' 2.718 225 5 2.580 130 8 113 k hr«B4i p p«orl7 raaclvad The reflections observed conform to: hkl only with h k even; hOl only w ith h + l even; OW) only with k even. These correspond to the space group CSa C2/c. This is in agreement with MgS04 • ÖH^O.