Beverly E. Robertson

Purification, growth, structure, optical and electrical properties of single crystals of the π‐molecular complex of phenothiazine with pyromellitic dianhydride

Single crystals of the black phenothiazine : pyromellitic dianhydride (PTZ:PMDA) 1:1 donor–acceptor complex, have been grown by sublimation from the zone‐refined components. The PTZ:PMDA complex crystalizes with P1 symmetry (Z=2), a=7.197(1), b=19.072(5), c=6.886(1) A, α=84.79(1) °, β=72.98(1) °, γ=85.72(2) ° at T=23 °C. The crystal structure model was refined with 5214 data { (sin ϑ/λ)max=0.8071 A−1} to give R=0.049 and Rw=0.089. The crystal packing consists of two polar endless ...DADA... stacks related to one another by 1. The packing is compared with that in the analogous anthracene : PMDA complex. The PTZ molecule displays a modest fold about the N...S axis (dihedral angle 176.4°), however, the deviation from planarity is small in comparison with that in PTZ crystals. The stack axis is nearly perpendicular to the molecular planes, consequently the CT‐dichroism lies essentially in the principal axis system of the indicatrix. The absorption edge is not very sharp, even at 4.2 K; it is located at 900±...

Closest packing in dense oxides: The structure of a polymorph of Co3(AsO4)2

Abstract Crystals of Co3(AsO4)2 were grown from the melt of a mixture of Co2As2O7 and As2O5. The crystals are isostructural with Mg3(AsO4)2 and are tetragonal with a = 6.858(2), c = 18.872(5) A, Z = 6, and space group I 4 2d . A total of 1048 independent reflections were measured by diffractometer and used in the full-matrix refinement to a final R value of 0.069. The structure contains two distinct AsO4 groups. Two of the cobalt ions are octahedrally coordinated and a third occupies a 4 site with four short and four long CoO distances. The crystal structure of Co3 (AsO4)2 is not based on the continuous three-dimensional closest packing of oxygen atoms. Nevertheless the number of oxygen atoms per cubic centimeter is 5.4 × 1022, which falls in the range of values for hexagonal and cubic closest packed structures. A better measure of the degree to which closest packing is achieved by a structure is suggested. It is based on an analysis of the polyhedra of oxygen atoms which surround each of the oxygen atoms in a structure and their relation to the polyhedra in ideally closest packed structures. In order to facilitate the analysis, polytopes of 11- and 12-vertex polyhedra were studied. A new decahexahedral 11-vertex polyhedron was found.

Preparation and structure of the 1:2 π‐molecular complex of phenothiazine with pyromellitic dianhydride

Single crystals of the black 1:2 donor–acceptor complex of phenothiazine with pyromellitic dianhydride, PTZ:(PMDA)2, were grown by plate sublimation at ∼163 °C from the zone‐refined components. The l:1 complex is produced at lower temperatures. Crystals of the 1:2 complex are monoclinic, P21/c, Z=4, a=7.689(3), b=12.953(5), c=28.14(2) A, β=104.30(2)° at T=19 °C. The structure was refined from 2863 x‐ray diffraction reflection intensities for which I>2.0σ(I) to R=0.064 and Rw=0.057. The structure consists of continuous ... DADA ... polar stacks as does the l:1 complex, but the stacks, which are parallel to the a axis, are separated in the c direction by the extra PMDA molecule. The overlap of adjacent molecules in the stack in the 1:2 complex is more closely related to the overlap of adjacent molecules in the π‐molecular complex of PMDA with anthracene. The resultant angle between the stack axis and the normal to the planar molecules is 27.1°. The geometry of the individual molecules in the l:2 complex is ...

Structural studies of 2,2-Diphenyl-1-picrylhydrazine: A clathrate forming compound

Abstract2,2-Diphenyl-1-picrylhydrazine was crystallized from both tetrahydrofuran and chloroform. The crystal structures of samples from both preparations were determined by X-ray diffraction at low temperatures. Both crystals are clathrates with solvent molecules included as guest species in a host framework formed by the diphenylpicrylhydrazine molecules. The structures are rhombohedral, space groupR3. For the crystal from tetrahydrofuran, at 228 K,a = 25.820(4),c = 15.096(2) Å,Z = 18,R = 0.084 andwR = 0.133. For the crystal from chloroform, at 115 K,a = 25.453(12),c = 15.083(3) Å,Z = 18,R = 0.117 andwR = 0.153. Each unit cell contains three cavities which have approximate cylindrical shape with diameter 7.8 Å and height 6.0 Å, and 3 point symmetry. The integrity of the host framework is maintained only through van der Waals forces rather than through intermolecular hydrogen bonding as is found in many other known organic cathrates. The conformation of the trinitroanilino group of the hydrazine molecule is similar to that in the related trinitroanilinocarbazole molecule. The N-N bond approximates a single bond, and both hydrazine N atoms aresp2 hybridized.

A Comparison of the High Resoluton Crystal Structures of the π- Molecuar Complexes of Anthracene and Phenothiazine with Pyromellitic Dianhydride

Abstract The π-molecular complexes formed by aromatic molecules with three rings tend to form crystals of high purity and are therefore ideal for solid state spectroscopic and photocurrent studies. We have therefore undertaken an investigation of the detailed structures of a number of such complexes in order to facilitate the interpretation of such data and other physical properties and in order to better understand the large changes in physical properties generated by small changes in composition and molecular packing. The piezoreflection spectra of the anthracene-pyromellitic dianhydride complex (A-PMDA) has been studied by Eckhardt and Merski (1973). The photo-current excitation spectra of A-PMDA was reported by Karl and Ziegler (1975) and more recently the preparation, optical properties, absorption and photoconductivity properties of phenothiazine-pyromellitic dianhydride have also been studied. (Anthonj, Karl, Robertson and Stezowski, 1979).

trans-Chlorobis(diphenylglyoximato)(tri-n-butylphosphine)cobalt(III)

The Co atom in the cobaloxime, [CoCl(C14H11N2O2)2(C12H27P)], is octahedrally coordinated to the two bidentate diphenylglyoximato ligands, approximating a plane with the Cl and P atoms located above and below the plane. The diphenylglyoximato moieties are themselves bent 6.6 (1) and 9.8 (1)° from the central plane of the four N atoms by the bulk of the tri-n-butylphosphine ligand. The four phenyl rings of the two diphenylglyoximato groups form a propeller geometry with an average rotation from the central plane of 47 (5)°.

Structure of 2,3-Naphthalenediamine Dihydrochloride Dihydrate

C 10 H 12 N 2 2+ .2Cl - .2H 2 O, M r =267. 15, monoclinic, P2 1 /c, a=7.057 (2), b=13.017 (3), c=13.982 (3) A, β=92.57 (4) o , V=1283.1 (5) A 3 , Z=4, D x =1.382 g cm -3 , λ(Mo Kα)=0.71069 A, μ=4.95 cm -1 , F(000)=560, T=298 K, final R=0.036, wR=0.026 for 1814 uniquely observed [I≥2σ(I)] reflexions. The organic moiety in the molecule is nearly planar and forms parallel stacks with the dipoles of adjacent molecules pointing in oppposite directions to each other

Structure of cis-1,2-diphenyl-2-tolylvinyl acetate

C 2 3 H 2 0 0 2 , M r 328.41, orthorhombic, Pbca, a = 13.121 (2), b = 3 0 . 1 8 1 (4), c = 9 . 2 9 1 (2)A, V-3679.3A 3, Z = 8 , D x = l . 1 9 g c m -3, 2 ( M o K a ) = 0.71069 A, g = 0.69 cm -~, T = 293 K, F(000) = 1392, final R = 0.043 for 2426 unique reflections. The acetate group is in an anticlinal antiperiplanar conformation. 0108-2701/87/040740-04501.50 accepted 3 November 1986) The molecule as a whole has a propeller conformation. The bond lengths and angles are similar to those in other triarylvinyl-X systems. Relative to the trans isomer, the cis isomer of 1,2-diphenyl-2-tolylvinyl acetate has the higher melting point and tolyl-CH 3 ~H NMR absorption at higher field.

Crystal structure and spectroscopy of 4-N-benzylaminocoumarin

The structure of 4-N-benzylaminocoumarin (C16H13NO2) has been determined by X-ray diffraction and the Ft-ir,1H- and13C-nmr spectra of the compound were recorded. Crystals of the compound are monoclinic, space group P21/c, with cell dimensiona=8.077(2),b=14.598(4),c=10.890(3) Å, and β=97.76(3)°. The Ft-ir and nmr spectra indicate that the nitrogen atom is in the amino form in solution. The crystal structure is consistent with this observation, but the C(3)−C(4) double bond is clearly delocalized to include the lone pair on the nitrogen atom.