Volume 207, Issue 1

The crystal structure of synthetic KFe[SeO 3 ] 2 was determined by single crystal X-ray diffraction methods: space group Pnma ( D 2h 16 ), a = 12.948(2) Å, b = 5.430(1) Å, c = 8.069(1) Å, V = 567.31 Å 3 , Z = 4; 1354 unique data, measured up to 2 θ = 70°; R , R w = 0.035, 0.031. The framework structure consists of KO 8 polyhedra, isolated FeO 6 octahedra and trigonal pyramidal SeO 3 groups.

MOLDRAW is a simple and easy to learn molecular graphics program running on personal computers, which allows drawing and manipulation of any molecular structure. In this article the program functions and examples of its application are presented. The user-friendly interface and the simple but powerful underlying logic are the main reasons for the widespread diffusion of MOLDRAW in the crystallographic and chemical community.

The molecular and crystal structure of the synthetic, terminally blocked, model dipeptide t -Boc-L-Val- Δ Ala-OMe ( 1 ) was determined by single-crystal X-ray diffraction. Crystal data for 1 are: C 14 H 24 N 2 O 5 , hexagonal, space group P 6 5 (no. 170), a = 10.800(2) Å, c = 27.077(2) Å, and Z = 6. The crystal structure was solved by direct methods. The least-squares refinement led to R and R w values of 0.077 and 0.075, respectively, for 1298 reflections with F ≥ 5 σ ( F ). The conformation of the Val residue is partially extended, while that of the Δ Ala residue is trans , cis . The N-terminal protecting group is in the trans , trans disposition.

The structure of a second crystal polymorph of silver(I) 2,6-dihydroxybenzoate, [Ag 2 ((OH) 2 · C 6 H 3 COO) 2 ] n has been determined by X-ray diffraction and refined to a residual R = 0.036 for 1332 observed reflections. Crystals are monoclinic, space group P 2 1 / n with two dimeric units in a cell of dimensions a = 7.090(1), b = 11.693(2), c = 8.164(1)Å, β = 90.58(1)°. As in the first reported polymorph, the structure contains centrosymmetric bis(carboxylato- O , O ′) bridged silver dimers. In the present structure, the dimers are cross-linked via Ag–O (hydroxyl) bonds [2.607(3)Å] to form a sheet polymer, whereas those in the earlier structure are discrete. Chelate-ring dimensions are essentially unchanged [Ag–O, 2.220, 2.236(3) cf. 2.203, 2.240(4)Í; Ag–Ag, 2.926(1) cf. 2.910(1)Å].

The title compound C 28 H 22 O 4 of molecular weight 422.46 crystallizes in the monoclinic system, space group C 2/ c , a = 27.56(2), b = 10.340(9), c = 18.25(2) Å, β = 122.52°(7), Z = 8, V = 4385.26 Å 3 , F (000) = 1776.00, D m = 1.277 gcm −3 , D x = 1.279 gcm −3 , linear absorption coefficient μ = 0.48 cm −1 . The crystal structure has been determined with a final agreement index R = 0.043 and R w . = 0.059 for 2531 independent observed reflections with I > 3 σ ( I ). X-ray studies revealed the difference in conformation of the two carbonyl groups and also confirmed the cis geometry of the molecule. The rotamer with s -cis conformation of C11 = C19 with respect to C7 = C8 is found to be the preferred one.

The known crystal structures of the mixed valence compounds In 6 S 7 and Sn 0.5 In 5 S 7 are characterized by the existence of indium atoms in different valence states: In + -ions (Sn 2+ ), dumbbell shaped In 2 4+ groups and In 3+ -ions. The In 2 4+ and In 3+ species are embedded in a characteristic coordination of sulfur atoms found separately in comparable simpler non-mixed-valence chalcogenides of indium. In 6 S 7 however is so far the only example with monovalent indium in a surrounding of sulfur. The question whether P 2 1 or P 2 1 / m is the correct space group for the description of In 6 S 7 (or Sn 0.5 In 5 S 7 ) cannot be answered clearly on the basis of the existing experimental data because it only affects a small possible deviation of the “lone pair cation” In + (Sn 2+ ) from a mirror plane. This may however be of great importance for futural studies of the physical properties. We prove the crystal structure of Sn 0.5 In 5 S 7 and In 6 S 7 to be actually isotypic. Moreover we show, that the pure tin containing compound does not exist, but is indeed In 6 S 7 in which In + -ions are partly (max. 50%) substituted by Sn 2+ .

Single crystals of p-aminohippuric acid (C 9 H 10 N 2 O 3 ) were obtained from an aqueous solution of the compound at room temperature. The crystals belong to the orthorhombic space group P 2 1 2 1 2 1 with a = 8.04(2), b = 10.24(4), c = 11.14(2) Å, V = 917.04 Å 3 , Z = 4, D m = 1.39, D x = 1.406 gm cm−1, λ (Cu Kα ) = 1.5418 Å, μ (Cu Kα ) = 0.86 mm −1 and F (000) = 408. Full-matrix least-squares refinement using 722 non-zero reflections yielded an R -value of 0.079. All the hydrogen atoms in the molecule could be located. The crystal structure is stabilized by a three-dimensional network of hydrogen bonds.

The crystal structures of the title compounds P , P -diphenyl- N -methyl-phosphinylthioformamide, [Ph 2 P(O)C(S)N(H)Me], and P , P -diphenyl- N -phenyl-selenophosphinylthioformamide, [Ph 2 P(Se)C(S)N(H)Ph], have been determined at room temperature. The pale-yellow crystals of [Ph 2 P(O)C(S)N(H)Me] are monoclinic, space group P 2 1 / c with unit cell dimensions a = 9.663(1), b = 14.073(2), c = 10.775(1) Å, β = 105.78(1)°, Z = 4 and D x = 1.297 Mg m −3 . The green crystals of [Ph 2 P(Se)C(S)N(H)Ph] are orthorhombic, crystallizing in the Pbca space group with dimensions a = 11.978(1), b = 8.772(5), c = 34.241(4) Å, Z = 8 and D x = 1.477 Mg m −3 . The structures were solved by direct-methods and Patterson methods, respectively and each refined by a full-matrix least-squares procedure to final R = 0.041 using 1474 reflections for [Ph 2 P(O)C(S)N(H)Me] and R = 0.046 using 1371 reflections for [Ph 2 P(Se)C(S)N(H)Ph]. The conformation about the C–N bond in [Ph 2 P(O)C(S)N(H)Me] is Z with important parameters: P = O 1.485(2), P–C 1.843(3), C = S 1.653(3) and C–N 1.313(4) Å. Centrosymmetric molecules associate in the lattice via hydrogen bonding contacts. A similar Z conformation is found in [Ph 2 P(Se)C(S)N(H)Ph] with important parameters: P = Se 2.108(2), P–C 1.871(7), C = S 1.634(8) and C–N 1.317(9) Å. The analysis of the geometric parameters defining the central chromophore indicate that the P–C bonds are comparatively weak in these phosphorus(V) compounds.

The new compounds Ln 6 Co 30 P 19 (Ln = Er, Tm, Yb and Lu) were prepared by reaction of the elemental components in a tin flux. They crystallize with a new structure type, which was determined from four-circle X-ray diffractometer data of Yb 6 Co 30 P 19 : space group P [unk] (No. 174), a = 1470.3(4) pm, c = 357.4(1)pm, Z = 1, R = 0.031 for 669 structure factors and 47 variable parameters. The structure is closely related to that of UCo 5 Si 3 (U 6 Co 30 Si 18 ) from which it can be derived by filling an additional atomic site on one six-fold axis with phosphorus atoms. This lowers the symmetry from the centric space group P 6 3 / m to the noncentric group P [unk] and doubles the number of positional parameters, all of which could be refined independently. Other examples with this space group ambiguity are given. Like Yb 6 Co 30 P 19 , many of these belong to a large family of structures with a metal to metalloid ratio close to 2:1.

The new ternary phosphides SrNi 9 P 5 and BaNi 10 P 6 were synthesized by heating the elements at 900°–1100°C. Single crystal X-ray methods revealed that SrNi 9 P 5 is isotypic with BaNi 9 P 5 and crystallizes hexagonally [ P 6 3 / mmc ; Z = 2; a = 6.529(1) Å, c = 10.732(1) Å], whereas BaNi 10 P 6 forms a new structure with orthorhombic symmetry [ Cmca , Z = 4; a = 6.449(1) Å, b = 16.191(1) Å, c = 8.784(1) Å]. The structures are best described as an arrangement of alkaline-earth metal atoms, which are surrounded by Ni 18 P 12 (SrNi 9 P 5 ) and Ni 14 P 12 cages (BaNi 10 P 6 ), respectively.

The crystal structures of two organic conductors di(3,5,8,10-tetramethyl-1,6-dioxapyrenium) tetrafluoroborate, (C 18 H 16 O 2 ) + 2 BF − 4 , and di(3,5,8,10-tetramethyl-1,6-dioxapyrenium) hexafluorophosphate, (C 18 H 16 O 2 ) + 2 PF − 6 , have been studied with single crystal X-ray diffraction methods. The two salts are isostructural and crystallize in the space group Pmna , Z = 2, with the unit cell parameters a = 6.772(1), b = 9.762(1) and c = 21.825(2) Å for the BF − 4 salt and a = 6.792(1), b = 9.769(1) and c = 22.096(3) Å for the PF[unk] salt. The models were refined to R -values of 0.082 (BF[unk]) and 0.069 (PF[unk]) using 860 and 979 reflections, respectively, with I > 2 σ ( I ). The tetramethyldioxapyrene molecules lie on mirror planes stacked along the a -axis with an interplanar distance of exactly a /2 (3.386 and 3.396 Å for the BF[unk] and PF[unk] structure, respectively). The BF[unk] anion exhibits considerable disorder whereas the PF[unk] anion is ordered, which is reflected in the higher R -value for the BF[unk] structure. Both salts are semiconductors.

The piezoelectric behaviour of Tl 3 BX 4 -crystals (B = V,Nb,Ta; X = S,Se) has been investigated. They show a very strong piezoelectric effect. The values of the piezoelectric modulus d 123 at 163 K range from 76.7 × 10 −12 m/V (Tl 3 VS 4 ) to 55.6 × 10 −12 m/V (Tl 3 TaSe 4 ). Apart from substances with ferroelectric phases, the Tl 3 BX 4 -compounds exhibit the strongest piezoelectric effect known.

l -histidinium phosphite, [C 6 N 3 O 2 H 10 ] + ·[HPO 3 H] − is monoclinic P 2 1 with crystal data: a = 8.497(7), b = 11.999(10), c = 4.967(3) Å, β = 104.15(6)°, V = 491(1) Å 3 and Z = 2. The crystal structure was solved with a final R value of 0.030 for 1780 independent reflections. The organic and phosphoric entities build layers parallel to the (100) plane. The [HPO 3 H] − groups, not held together by H-bonds, are linked by O–H⋯O and N–H⋯O bonds to the histidine groups. The latter are laced together by N–H⋯O bonds to form chains running parallel to b . In addition to this study, the atomic arrangement of the monoclinic form of l -histidine was reinvestigated, this time with an untwinned crystal. The space group is P 2 1 with a = 5.166(6), b = 7.385(5), c = 9.465(4) Å, β = 98.16(5)°, V = 357.4(9) Å 3 and Z = 2. The new refinement, based on 1182 independent reflections, led to a final R value of 0.039. A description of the structure, including the H-bond scheme, is given. In addition to an improvement of the experimental accuracy, some H atoms, not found in the first study were located. The main structure is in general agreement with that from the previous investigation.

The title compound was prepared by a TiCl 4- catalyzed reaction of bisacetylated benzene and 1-phenylethylamine. It crystallizes from ethyl acetate/petroleum ether orthorhombically in the space group P 2 1 2 1 2 with a = 796.2(1), b = 1908.7(5) and c = 924.1(2) pm.

The title compound was prepared by Wittig-reaction of 1-bromo-2-formylnaphthalene and (3,5-dimethoxyphenyl)-methylene phosphorane. It crystallizes from dichloromethane/petroleum ether monoclinically in the space group P 2 1 / n with a = 1493.4(6), b = 842.3(2), c = 1485.0(6) pm and β = 117.95(3)°.

The title compound was prepared from the corresponding Z - (i.e. cis -) configurated stilbene-like olefin, by an osmium-catalyzed dihydroxylation reaction. It crystallizes from chloroform/petroleum ether monoclinically in the space group P 2 1 / a with a = 2282.2(9), b = 517.9(2), c = 772.8(2) pm and β = 93.25(2)°.

The title compound was prepared by N -benzylation of the corresponding secondary amine and transformation into its hydrobromide. It crystallizes from ethanol orthorhombically in the space group P 2 1 2 1 2 1 with a = 1128.4(4), b = 2162.6(7), c = 769.2(2) pm.