Edward N. Maslen

Crystal structure of bis-(2,2′ :6′,2″-terpyridyl)cobalt(II) bromide trihydrate

The crystal structure of the title compound has been determined by Patterson and Fourier methods from single-crystal X-ray diffractometer data, and refined by least squares to R 0·096 (2704 reflections). Crystals are triclinic, probable space group P, a= 19·763(4), b= 9·563(2), c= 8·537(1)A, α= 95·96(1), β= 93·48(1), γ= 94·44(1)°, Z= 2. Within the cation, each terpyridyl ligand co-ordinates via the three nitrogen atoms, the central Co–N distance being shorter than the outer [〈Co–N〉, 1·89, 2·10(1)A respectively] and the ligand being strained to accommodate the bonding; the overall cation symmetry is approximately D2d. The bromide ions are disordered between lattice sites ca. 2·0 A apart; the potential barrier between the two sites appears small and may be the determinant of the ‘crossover’ situation which exists in this complex.

The structure of bruceol

Abstract A novel coumarin bruceol, has been isolated from Eriostemon brucei F. Muell. Preliminary chemical studies have been made and the complete structure determined by X-ray crystallography of a monobromo derivative.

Crystal structure of aqua(2,2′ :6′,2″ :6″,2‴-quaterpyridyl)sulphitocobalt-(III) nitrate monohydrate

The crystal structure of the title compound has been determined by the heavy-atom method from X-ray diffracto-meter data and refined by block-diagonal least-squares to R 0·056 for 1891 observed reflections. Crystals are monoclinic, space group P21/n, a= 19·005(4), b= 15·598(3), c= 6·913(1)A, β= 92·34(1)°, Z= 4.The quaterpyridyl ligand is planar and coplanar with the cobalt, the inner nitrogen atoms bonding to it at a shorter distance (1·855 ± 0·005) than the outer (1·97 ± 0·01 A). Co–OH2 is 2·067(5) and Co–S 2·244(2)A. The nitrate ion is disordered.

Crystal structure of an epoxycembradienol, 3,15-epoxy-4-hydroxycembra-7(Z), 11(Z)-diene

Abstract The crystal structure of the title compound, C20H34O2, has been determined by single crystal X-ray diffraction methods at 295 K from diffractometer data using direct methods and refined by least squares to a residual of 0.06 for 2152 “observed” reflections. Crystals are orthorhombic, P212121, a = 32.770(8), b = 10.960(3), c = 10.850(3) A, Z=8. The asymmetric unit comprises two independent molecules, both of which confirm the structure proposed in the preceding paper.

Crystal structure of catena-di-µ-acetylacetonato-cadmium(II)

The crystal structure of the title compound has been determined from single crystal X-ray diffractometer data, and refined by full-matrix least-squares R 0·042 for 1105 observed reflections. Crystals are monoclinic, space group P21/a, a= 18·832(8), b= 7·012(3). c= 8·531(3)A, β= 96·08(3)°, Z= 4. The structure is comprised of linear chains of cadmium atoms spaced at 3·768(2) and 3·718(2)A; the cadmium atoms are bridged by one oxygen atom from each ligand [Cd–O 2·288–2·353(4)A] the remaining two co-ordination sites about the six-co-ordinate cadmium being occupied by the other two non-bridging oxygen atoms [Cd–O 2·221, 2·250(4)A].

Crystal structure of the tricyclic diterpene derivative 18-hydroxydecipia-2(4),14-dien-1-oic acid

The crystal structure of the title compound, a new tricyclic diterpene derivative extracted from Eremophila decipiens containing the tricyclo[5.3.1.05,11]undecane ring system, has been determined by X-ray diffraction from diffractometer data and refined by least squares to R 0.062 for 1 065 reflections with l > 3σ(l). Crystals of the derivative, C20H30O3, are orthorhombic, space group P212121, a= 36.95(2), b= 7.467(5), c= 6.676(5)A, Z= 4.

Crystal structures of (5E,12E)-7β-acetoxy-15β-hydroxybertya-5,12-diene-3,14-dione and (5E,12E)-7β-acetoxybertya-5,12-diene-3,14-dione

The crystal structures of the title compounds, C22H30O5(I) and C22H30O4(II), have been determined by X-ray diffraction by direct methods and refined by least squares to R 0.036 and 0.043 for 1 211 and 1 204 reflections respectively. Crystals of (I) and (II) are both orthorhombic, space group P212121, Z= 4; for (I), a= 23.095(3), b= 10.987(1), c= 8.224(1)A; for (II), a= 21.199(4), b= 11.160(3), c= 8.998(2)A. The structure determinations confirm the stereochemistry previously assigned by other chemical and physical methods to the novel diterpene, bertyadionol.

Crystal structure of trans-aquabis(ethylenediamine)sulphitocobalt(III) perchlorate monohydrate

The crystal structure of the title compound, previously reported as having one less molecule of water, has been determined from X-ray diffractometer data and refined by least squares to R 0·080 for 1455 observed reflections. Crystals are monoclinic, space group P21/n, a= 11·210(3), b= 13·626(2), c= 9·727(3)A, β= 105·17(2)°, Z= 4. Interatomic distances are: mean Co–N 1·94, Co–S 2·181(3), Co–O 2·037(7), mean Cl–O 1·41, and mean S–O 1·46 A. The Co–OH2 distance is long, presumably as a consequence of the trans-effect of the sulphite ligand.

Crystal structure of 3-methyl-5-phenylpyrazole

The crystal structure of the tautomeric title compound, C10H10N2, has been determined by direct methods from X-ray diffractometer data, and refined by least squares to R 0·060 (1614 reflections). Crystals are monoclinic, space group C2/c, a= 19·841(6), b= 12·000(2), c= 15·079(4)A, β= 92·58(2)°, Z= 16 (two independent molecules in the asymmetric unit).The geometry of the molecule is as expected; interaction between the pyrazole substituents in each case imparts a twist (21·35 and 18·21°) about the bond between the phenyl and pyrazole rings. The molecules are clustered in groups of four about the two-fold axes of the cell with the pyrazole nitrogen atoms directed toward, or close to, that axis. It has not been possible to locate the NH hydrogen atoms, which are presumed to exist as a loose association within each molecular grouping.

Stereochemistry of the MX4Y system (M = metal; X = unidentate, Y = bidentate ligand): crystal structure of tetrachloro-[1,2-bis(dimethylarsino)-3,3,4,4-tetrafluorocyclobut-1-ene]rhenium(IV)

The title compound has been prepared and its crystal structure determined by the heavy-atom method from diffractometer data; it was refined by full-matrix least-squares to R 0·045 (949 independent observed reflections). Crystals are monoclinic, space group P21, a= 8·834(2), b= 16·090(4), c= 6·596(1)A, β= 109·78(1)°, Z= 2.Mean distances are: ReIV–As 2·560(4), ReIV–Cl 2·32(1)A. The geometry is considerably distorted from octahedral; this is generally true for [M (bidentate)(monodentate)4]x± compounds and a repulsion model has been developed to account for this.