Volume 171, Issue 3-4

The compound p-methoxy phenyl, p′-methoxy phenyl, 1:1 dichloro methane crystallises in the monoclinic space group C 2/ c with unit cell parameters a = 18.290(4), b = 7.963(5), c = 11.096(3) Å, β = 115.74°(2), cell volume = 1455.6 Å 3 , d c = 1.38 gcm −3 , d 0 = 1.40 gcm −3 , μ (Mo Kα ) = 4.45/cm, F 000 = 784 and z = 4. The gross structure was determined by applying the Patterson synthesis method, which on refinement yielded R = 0.035.

The crystal structure of C 19 H 14 N 2 O 7 S has been determined by the single-crystal X-ray analysis. The crystals are monoclinic, space group P 2 1 [ a = 12.429(2), b = 4.762(1), c = 15.689(2) Å, β = 97.27(1)°, Z = 2, D c = 1.49, D m = 1.48 g cm −3 , μ (Cu Kα ) = 1.86 mm −1 ]. The structure was refined to R = 0.0441 and R w = 0.0414 by full-matrix least-squares method using 1189 reflections. The absolute configuration at the sulphur atom was found to be R .

The crystal and molecular structure of the title compound is reported. Crystals are triclinic, space group P [unk] with Z = 4 in a unit cell of dimensions a = 8.835(1), b = 14.294(2), c = 14.570(2) Å, α = 107.15(1), β = 95.50(1) and γ = 100.97(1)°. The structure was solved by the heavyatom method and refined by the full-matrix least-squares method to R = 0.060 for 3091 unique reflections. The Cd atoms of both the molecules in the same asymmetric unit have distorted octahedral configuration. Both the molecules in the same asymmetric unit have the λλλ ring conformation.

The crystal structure of a new sulphosalt, jaskolskiite, Cu x Pb 2+ x (Sb, Bi) 2− x S 5 ( x ≈ 0.2), has been determined. The space group is Pbnm , with a = 11.312(2), b = 19.829(3), c = 4.088(1) Å, Z = 4 for the composition Cu 0.19 Pb 2.22 Sb 1.17 Bi 0.62 S 5 . The structure has been solved using its homologous relationship to meneghinite and refined from three-dimensional diffractometer data to an R -value of 0.072 for 472 observed reflections. The structure consists of slices (010) of SnS-like arrangement mutually related by the n -glide planes and wavy interfaces. The metal positions M1 and M4 inside the slices represent Sb sites partly substituted by Bi and Pb. The M2 and M3 positions are on the surfaces of slices and represent Pb sites with some substitution by Bi in the case of M2. The tetrahedral sites in the slice interfaces are partially occupied by Cu. Jaskolskiite represents the 4th member of the meneghinite homologous series. The published chemical and structural data for the known homologues of meneghinite, with N = 1, 2, (3), 4 and 5, are systematized in the paper.

2-hydroxy, 4-amine, w – w′, dichloroacetophenone crystalizes in the monoclinic space group P 2 1 / a with unit cell parameters a = 7.458(2), b = 9.109(1), c = 13.3997(26) Å and β = 99°.86(2), Cell vol. = 896.905 Å 3 , d c = 1.63 g/ml, d o = 1.65 g/ml, μ (Mo Kα ) = 6.86 cm −1 , F 000 = 480 and with four molecules per unit cell. The gross structure was confidently predicted in applying ‘Patterson synthesis’ method, which yielded R = 0.044 and S = 1.28, S , being the standard deviation of an observation with unit weight.

Diaquabisglycinecobalt(II) bromide crystallises in the monoclinic system, space group P 2 1 / a with a = 8.822(1), b = 6.0552(4), c = 11.771(1) Å, β = 111.53(5)° and Z = 2. The intensity data were collected using a CAD-4 automatic diffractometer with Mo Kα radiation. The structure was determined by Patterson and Fourier methods. A leastsquares refinement led to an R value of 0.065 using 1595 reflections. Cobalt is coordinated to six oxygen atoms, four from the glycine molecules and the rest from the water molecules, forming an octahedron with minimal distortions. The bromine atoms do not coordinate with cobalt, but fill in the vacant spaces and participate in hydrogen bonding. The glycine molecules exist in this crystal as zwitterions, NH 3 + CH 2 COO − .

The crystal structures of the green compounds CrF 3 · 3H 2 O and CrF 3 · 5H 2 O have been determined. The first is rhombohedral [ a R = 5.668(4) Å, α R = 112.5(1)°, space group R [unk] m , Z = 1] and the second orthorhombic [ a = 10.396(5), b = 8.060(5), c = 7.965(4) Å, space group Pbcn , Z = 4]. Both compounds contain the same octahedral molecules Cr[F 3 (H 2 O) 3 ], but the nature of the isomers present could not be determined because of crystal disorder. There is extensive hydrogen bonding in both types of crystal. It has been found that violet Cr[H 2 O] 6 F 3 · 3H 2 O decomposes thermally to green Cr[F 3 (H 2 O) 3 ] in three stages, with violet Cr[H 2 O] 6 F 3 identified as the product formed in the first stage.

The structure of the title compound, C 7 H 5 NS 2 , was re-determined in order to verify the presence of any discrepancies like shorter bond-length between two of the carbon atoms or the presence of unusual hydrogen bonding which were reported in the earlier literature. The crystals are monoclinic, space group P 2 1 / n with cell parameters a = 8.014(2) Å, b = 6.004(2) Å, c = 15.393(2) Å, β = 100.72(2)°, D c = 1.526 g cm −3 , which agree well with those reported earlier. The present work does not have the discrepancies reported earlier. The structure was refined by full-matrix least-squares refinement to a final R = 0.035 for 1017 unique reflections.

The crystal structure of the title compound M = 653.07 has been determined. Crystals are orthorhombic, space group Pbca with a = 22.320(9), b = 16.257(7), c = 14.503(7) A, Z = 8, D x = 1.649(4), D m = 1.70 Mg/m 3 . The crystal structure was determined by the heavy-atom method and refined to R = 0.065 and R w = 0.066. Nickel(II) atom is surrounded by five nitrogen atoms and one oxygen atom of the water molecule forming an irregular octahedron.

Crystal and molecular structure of mesitil, C 20 H 22 O 2 , was preliminarily determined from visually estimated two-dimensional X-ray diffraction data from the study of weighted recriprocal lattice and Patterson projections. The structure was refined with 1901 data observed [ I > 3 σ ( I )] by diffractometry ( R = 0.0518 and R w = 0.0476). The space group is Pbca with a = 23.982(9), b = 16.593(7), c = 8.683(5) Å; the unit cell contains eight formula units; the measured density was D m = 1.134 and the calculated density was D c = 1.135 · cm −3 . The two carbonyl moieties have a transoid geometry making a dihedral angle of 178.27° while the mesityl planes are forced out of the adjacent carbonyl planes by 75.35° and 78.30°.

Single crystals of CdGeO 3 ilmenite have been synthesized at p = 10.3 GPa and T = 1200°C. The crystal structure of CdGeO 3 ilmenite has been determined with 781 counter-measured intensities and refined by the least-squares method to R = 0.048. CdGeO 3 ilmenite is trigonal with a = 5.0988(4) Å, c = 14.932(3) Å; R [unk] and Z = 6. Cd 2+ and Ge 4+ ions occupy alternate basal-plane layers of cationic sites, and there is no observed disordering of Cd 2+ and Ge 4+ ions. The mean distances of Cd – O and Ge – O are 2.321 Å and 1.921 Å, respectively, in good agreement with those expected from the effective ionic radius of Cd and Ge in six-fold coordination. The height of the CdO 6 octahedra along the c axis is about 30% greater than that of GeO e octahedron. Crystal-chemical analysis of the ilmenite-type compounds suggests that c is chiefly affected by the size of divalent cations in the ilmenite structure, while a is dominantly controlled by the size of the tetravalent cation. CdGeO 3 ilmenite has the largest value of c / a among compounds with the ilmenite structure, as a result of its largest difference in ionic radius between paired cations.

The computer plot program UMWEG calculates and plots the positions and intensities of all operative reflections for a rotation of 360 degrees around the scattering vector of a chosen primary reflection.

The crystal structure of manganese (II) L-tartrate tetrahydrate has been determined and refined by three-dimensional least-squares methods. The crystals are orthorhombic, space group P 2 1 with a = 6.092(5), b = 12.285(7), c = 7.285(4) Å, β = 112°, and two molecules per unit cell. Photographic data refined to R = 0.078. Each manganese atom is surrounded by six oxygen atoms, four from two chelate rings of two tartrate ions, two water molecules.

The crystal structure of Sb 2 Se 3 has been redetermined with 610 independent reflections, using three-dimensional intensities measured on a computer-controlled Philips PW 1100 single-crystal diffractometer. The structure does not deviate in principle from that proposed by Dönges (1950) and Tideswell, Kruse, Mc Cullough (1957), but it shows interesting details. The cell constants, obtained by least-squares calculation from direct θ -value measurements on the diffractometer, are: a = 11.7938(9), b = 3.9858(6), c = 11.6478(7) Å, Z = 4; the space group is Pnma . The positional and thermal parameters, with anisotropic temperature factors, were refined by full-matrix, least-squares calculations to a final R = 0.052. Sb 2 Se 3 is isostructural with Sb 2 S 3 and Bi 2 Se 3 . Each Sb(1) atom is six-coordinated by 2 Se(1), 3 Se(2), 1 Se(3) atoms, in the form of a strongly distorted octahedron, at distances 2.664 to 3.248 Å ( P 1 polyhedron). The Sb(2) atoms, however, are seven-coordinated by 3Se(l), 2Se(2) and 2Se(3) atoms at distances 2.589 to 3.485 Å ( P 2 polyhedron). The four Se atoms [2Se(1), 2Se(3)] form a rectangle parallel to (010), which constitutes the base of a tetragonal pyramid whose apex is Se(1). The two remaining Se(2) atoms, together with those of the rectangle, form a triangular prism perpendicular to (010). Each P 1 octahedron is linked to a symmetry-equivalent polyhedron by a common Se(2), Se(2) edge to form a double polyhedron unit, which is further linked to other P 1 double polyhedra along the b axis in infinite chains. In an analogous way, two symmetry-related P 2 composite polyhedra are linked by a common Se(1), Se(1) edge to form a double polyhedron, which is linked to other double polyhedra along the b axis, resulting again in an infinite chain. Each P 1 chain holds together four neighboring parallel P 2 chains and each P 2 chain in its turn holds together four neighboring parallel P 1 chains.

Complete sets of elastic and thermoelastic tensor components of triclinic NaHC 2 O 4 · H 2 O have been determined by ultrasonic resonance methods. The crystals exhibit a strong elastic anisotropy of more than a factor of three. In contrast, the thermoelastic constants behave nearly isotropically. The minimum of longitudinal elastic stiffness and the maximum of thermal expansion are observed in a direction almost perpendicular to the cleavage plane (001). Most effects of anisotropy are closely related to the system of hydrogen bond chains within the cleavage plane.

The crystal structure of norsethite, BaMg(CO 3 ) 2 , [ a = 5.022(1) Å, c = 16.77(1) Å, space group R [unk] m , Z = 3] was reinvestigated by single crystal X-ray methods working with both natural and synthetic material. The main features of an earlier structure determination using powder data were confirmed, but no significant deviation of the atomic arrangement from R [unk] m was found. The carbonate group is aplanar; the most probable value for the distance of the carbon atom from the plane defined by the three oxygen atoms is estimated to be 0.044(7) Å.

The crystal structure of the new zeolite mineral gobbinsite, Ca 0.6 Na 2.6 K 2.2 Al 6 Si 10 O 32 · 12H 2 O, has been determined in the space group Pmn 2 1 with a = 10.108(1), b = 9.766(1) and c = 10.171(1) Å. The topology of the framework is the same as that of gismondine and can be described as a stacking of 2-dimensional arrays of double crankshaft chains. The structure was refined by the Rietveld technique using X-ray powder data, and converged with R F = 0.126 and R wp = 0.136 (statistically expected R e = 0.121). Fifty soft restrictions on the bond distances and angles of the aluminosilicate framework atoms were included in the least-squares refinement as additional (geometric) observations. This facilitated the location of the non-framework cations and water molecules, and improved the stability of the refinement. As in the closely-related synthetic zeolite Na – P2, the pseudo-tetragonal axis of the gismondine-type framework is parallel to one of the near-equivalent unit cell dimensions ( c -axis), not to the unique one as expected. The arrangement of cations within the zeolitic channels suggests an explanation for this distortion of the ideally tetragonal framework.

Using a miniature diamond-anvil pressure cell and by means of single-crystal four-circle diffractometry, the crystal structure of synthetic forsterite has been studied up to 149 kb. The results are: (1) the distortion of the oxygen lattice from that of an ideal hexagonal closest packing (hcp) decreases with an increase of pressure, the extrapolation of the variation mode showing that the oxygen lattice would be ideally of the hcp type at around 160 kb. (2) While the mean Mg(2) – O bond shows a linear decrease with an increase of pressure, the mean Mg(1) – O distance ceases decreasing at around 80 kb. The value at this pressure is kept constant up to the experimental limit of 149 kb. At this extreme pressure both mean values are 2.05 Å. (3) The bulk modulus for the mean Si – O bond shows a value of 1.9 Mb.

The crystal structure of trans -nonachlor has been determined by X-ray diffraction at 298 K and refined to a residual of 0.030 for 999 observed reflections. Crystals of the title compound are orthorhombic, space group P 2 1 cn with 4 molecules in a cell of dimensions a = 7.721(4), b = 11.379(6), c = 18.507(10) Å. The analysis confirms the aaa conformation for the three chlorine substituents on the cyclopentane ring while the hexachloronorbornene nucleus is structurally very similar to other known ‘cyclodiene’ compounds.

The title compound crystallizes monoclinically in the space group P 2 1 , with a = 1674.1(5), b = 1117.8(4), c = 1282.0(3) pm, β = 103.42(2)°, and Z = 4. The crystals are built up of discrete molecules, the palladium atom having approximate square planar coordination with the nitrogen and phosphorus atoms in cis-position. The lengths of the Pd – N (218.4 pm) and Pd – P (232.1 pm) bonds are compared with those of similar compounds.