Timothy J.R. Weakley

THE CRYSTAL STRUCTURE OF AMMONIUM β-OCTAMOLYBDATE PENTAHYDRATE

Abstract X-ray structure analysis (film data, R = 0.080 for 1568 reflections) has confirmed the structure of the anion in (NH4)4[Mo8O26], 5H2O, deduced by Lindqvist in 1950 from the Mo coordinates alone. The compound is triclinic, P 1 , a = 9.769(16), b = 9.832(13), c = 7.848(11) A, α = 99.11(4), β = 101.03(11), γ = 97.40(4)°, Z = 1. Eight MoO6 octahedra share edges in a compact grouping, with short terminal MoO bonds (1.69 to 1.75 A), longer bonds (1.88–2.00 A) to bicoordinate O atoms, and long bonds (2.18–2.39 A) to multiply-shared interior atoms.

The Crystal structures of three adducts of lanthanide nitrates, water and 4,4′-bipyridyl: [La2(H2O)7(NO3)6]·4C10H8N2, [Ho(H2O)3(NO3)3]·2C10H8N2 and [Y(H2O)3(NO3)·2C10H8N2

Abstract Three classes of adducts of aqua-nitratolanthanide complexes and 4,4′-bipyridyl (4-bipy) have been structurally characterised: (1) [Ln2(H2O)7(NO3)6]· 4(4-bipy), Ln = La, Ce(III), Pr; (2) [Ln(H2O)3(NO3)3]·2(4-bipy), Ln = Y, Ho; (3) [Ln(H2O)3(NO3)3]·2(4-bipy), Ln = Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho. In all cases, nitrate groups are bidentate, and 4-bipy molecules are un-protonated and un-coordinated and are hydrogen-bonded to ligand water molecules. in (1), a doubly-bidentate NO3 group bridges two Ln atoms. Crystal data include: (1) (Ln = La). Cmc21, a = 24.52(2), b = 16.673(12), c = 13.245(8) A, Z = 4, diffractometer data, R = 0.094 for 3241 reflections; (2) (Ln = Ho), Pbca, a = 7.731(7), b = 43.77(8), c = 15.67(3) A, Z = 8, film data, R = 0.060 for 2124 reflections; (3) (Ln = Y), P21/c, a = 7.910(6), b = 20.81(2), c = 16.56(2) A, β = 104.60(5)°, film data, R = 0.058 for 2820 reflections.

Diels–Alder route to potential trichothecene precursors

2-Methylbut-3-yn-2-ol (9) is efficiently converted into 6-formyl-3,6-dimethylcyclohex-2-enyl acetate (4b) and into 6-acetyl-3,6-dimethylcyclohex-2-enyl acetate (4c)via highly regio- and stereo-selective Diels–Alder cycloadditions of 3-methylbuta-1,3-dienyl acetate (2b). The cycloadduct (4b) is converted by base into 4a,5,6,8a-tetrahydro-4a,7-dimethylcoumarin (13b), whilst the cycloadduct (4c) yields 2,3,4a,5,6,8a-hexahydro-2-hydroxy-2,4a,7-trimethylchroman-4-one (15), the structure of which was confirmed by X-ray analysis. Both (13b) and (15) possess a number of structural features of the trichothecenes and may be of value in their total synthesis.

The crystal structures of 4,4′-bipyridinium μ-(4,4′-bipyridine)bis[diaquatetranitratoneodymate(III)]-tris(4,4′-bipyridine) and a second monoclinic form of triaquatrinitratoholmium(III) – bis (4,4′-bipyridine)

Abstract The structures of (4-bipyH) 2 [(μ-4-bipy)Nd 2 (NO 3 ) 8 (H 2 O) 4 ]·3(4-bipy) (4-bipy = 4,4′-bipyridine; P 2 1 /c, a = 18.723(10), b = 10.720(6), c = 18.027(10) A, β = 94.43(5)°, Z = 2; R = 0.066 for 4931 (diffractometer data) and of a second monoclinic form of [Ho(NO 3 ) 3 (H 2 O) 3 ]·2(4-bipy) ( P 2 1 / c , a = 15.830(10), b = 21.44(3), c = 15.70(3) A, β = 100.4(2)°, Z = 8; R = 0.091 for 2335 film data) are reported. In the first compound pairs of Nd atoms are bridged across a crystal inversion centre by a 4-bipy ligand, and 10-coordination is completed by one monodentate NO 3 , three bidentate NO 3 , and two H 2 O ligands, with bond lengths NdN 2.70, NdOH 2 (av.) 2.44, NdO(NO 3 , av.) 2.56 A. The second compound has a variant of the previously-reported monoclinic [Y(NO 3 ) 3 (H 2 O) 3 ]·2(4-bipy) structure, with doubling of the unit cell on a but with essentially no change in the geometry and orientation of the nine-coordinate complex. In both compounds the non-coordinated, non-protonated 4-bipy N atoms form hydrogen bonds with ligand H 2 O.

The crystal structures of 4,4′-bipyridinium(+1) tetranitratodiaqua(4,4′-bipyridyl)neodymiate(III) and trinitratotetraaquaytterbium(III)-4,4′-bipyridinium(+1) nitrate ()

Abstract The structures of (C10H9N2)[Nd(NO3)4(H2O)2(C10H8N2)][P212121, a = 7.214(4), b = 19.928(9), c = 18.515(9) A, Z = 4; R = 0.066 for 3481 reflections] and Yb(NO3)3(H2O)4·2(C10H9N2)(NO3) [P 1 , a = 15.184(10), b = 12.755(12), c = 7.156(10) A, α = 79.75(13), β = 78.49(5), γ = 95.09(5)°, Z = 2; R = 0.076 for 3349 reflections] have been solved from, respectively, diffractometer and film data. In both compounds, ligand NO3 groups are bidentate. In the Nd compounds, one 4,4′-bipyridyl is protonated, and the other is a ligand; Nd is 11-coordinate, with bond lengths NdO(NO3)(av.), 2.626; NdOH2 (av.), 2.484; NdN, 2.767 A. In the Yb compound, both bipyridyls are protonated and un-coordinated; Yb is 10-coordinate, with YbO(NO3)(av.), 2.592; YbOH2(av.) 2.471 A. There is extensive hydrogen bonding in three dimensions in both compounds. The Nd compound has a Pr isomorph, and the Yb compound has a Nd isomorph.

The crystal structures of two Heteropolytungstate salts containing anions derived from α-octadecatungstodiphosphate(6-): (NH4)10[α2-P2W17O61]·8H2O and (ME2NH2)8[α2-P2Co(H2O)W17O61]·11H2O

Abstract The anions in (NH4)10[α1-P2W17O61]·8H2O (I) and (Me2NH2)8[α2-P2Co (H2O)W17O61]·11H2O (II) both have the [α-P2W18O62]6− structure with one “cap” W atom and its terminal oxygen atom missing (I), and a Co(H2O)2+ group in place of one “cap” W atom and its terminal oxygen (II). Both anions have approximate mirror symmetry but are disordered in the crystal; inI the anion lies on a crystal inversion centre in two equally-weighted orientations, and inII the Co atom appears as two Co0.5W0.5 composite atoms on either side of a crystallographic mirror plane. Crystal data include [diffractometer, Mo radiation, and ¦F¦>/3σ(F)]:I, Cmca, a = 18.080(8), b = 17.945(7), c = 21.546(8)A, Z = 4, R = 0.067 for 1384 data;II, Pnam, a = 28.052(11), b = 15.069(12), c = 20.638(17)A, Z = 4, R = 0.069 for 3057 data.

The crystal structures of rubidium 20-tungstocobalto(II)diarsenate(III) hydrate, Rb8[As2CoW20O68(OH2)2]·10H2O, and its zinc analogue

Abstract The anions in Rb 8 [As 2 CoW 20 O 68 (OH 2 ) 2 ]·10H 2 O (I) and Rb 8 [As 2 ZnW 20 O 68 (OH 2 ) 2 ]·12H 2 O(II) have the As 2 W 21 O 69 (OH 2 ) 6− structure, with substitution of Co or Zn for one of the W atoms in squarepyramidal coordination in the equatorial belt of the As 2 W 21 anion. Thus, two α-B As III W 9 O 33 9− moieties are linked via a Co(OH 2 ) 2+ , a WO 4+ and a WO(OH 2 ) 4+ group whose total coordination numbers are respectively 5,5, and 6. If the replacement of W by Co or Zn is ignored, the anions have mm symmetry, but conform to the crystal three-fold axes as the result of disorder in the equational belt. The crystal data include: space-group R 3 , Z = 6; I(II), a = 20.035(6) (20.030(5)), c = 32.8449(10) (32.80(1)) A; R = 0.092 (0.092) for 3026 diffractometer data (1762 film data).

Phosphorus standards for the electron probe X-ray microanalysis of ultrathin tissue sections

Phosphorus‐containing standards for use during quantitative electron probe X‐ray microanalysis of ultrathin tissue sections can be quickly and simply prepared using organo‐phosphorus compounds which are soluble in Spurrs epoxy resin mixture. Trials of five such compounds (one solid, the rest liquid) are described.

Crystal structure of cesium aquanickelo(II)undecatungstophosphate dihydrate

The title compound, Cs5[PNi(H2O)W11O39]·2H2O, is tetragonal with space groupP42/ncm and cell dimensionsa=20.908(5),c=10.391(6) Å. The single-crystal structure determination (diffractometer data, Mo radiation,R=0.054 for 1484 unique reflexions) shows that two types of disorder are present: the Ni atom substituting for W in the parentα-PW12O403− anion is distributed equally over all twelve W sites and, in addition, the anion lies at a crystal site of symmetry 2/m in two equally weighted orientations related by the two-fold axis. The dimensions of the anion are normal.

Branched-chain sugars. Part 8. The synthesis of C-acetylpyranosides and a pillarose derivative using 1-methoxyvinyl-lithium

1-Methoxyvinyl-lithium, a masked acylating agent, added to the protected hexopyranosiduloses (1), (4), and (7) to give adducts that were readily hydrolysed with acid to the C-acetyl derivatives (3), (6), and (9), respectively. The 1-methoxyvinyl adduct (13) derived from methyl 2,3,6-trideoxy-α-L-glycero-hexopyranosid-4-ulose (12) gave methyl 42-O-benzoyl-α-L-pillaroside (16), following oxidation with m-chloroperbenzoic acid in wet ether and benzoylation of the resulting 4-C-glycoloyl derivative (15).