Volume 226, Issue 10 -

In this paper, orbit colorings of a lattice Λ were considered, extending the idea of obtaining lattice colorings based on cosets of a sublattice. Given a subgroup S of finite index in the symmetry group G of the lattice Λ, if T ( S ) is the subgroup of translations in G and L is the sublattice of Λ determined by T ( S ), then a homomorphism f from N = N G ( T ( S )) to the subgroup S C of permutations of the cosets of L in Λ is defined. This homomorphism was used to obtain S -orbit colorings of Λ and the corresponding color group H and color fixing group K . Moreover, S ker f ≤ K ≤ H ≤ N .

A two-component salt containing an [Mn III 4 O 2 (OAc) 7 (phen) 2 ] + (OAc -0 = acetate, phen = 1,10-phenanthroline) cation, a 2,3-dihydro-1,3-benzothiazol-2-iminium cation, acetate anions and acetic acid molecules was synthesized and characterized. The presence of protonated 4-aminobenzothiazol causes structure directing intermolecular stacking and hydrogen bonds.

Large single crystals with optical quality of bis(hexylammonium) zirconium bis (nitrilotriacetate) dihydrate with dimensions up to about 15 cm 3 were grown from aqueous solutions. The complete elastic stiffness tensor was determined at 293 K. The propagation velocities of ultrasonic modes which are strongly related to the elastic constants c 11 , c 22 , c 33 , and c 66 , displayed anomalous behaviour between 260 K and 300 K. We observed distinct anomalies in the temperature dependent evolution of the elastic coefficient c 22 as indicated by a drastic change of the thermoelastic constant T 22 between about 275 K and 295 K. No discontinuity of any ultrasonic wave velocity and no anomalous attenuation effects have been measured in the temperature range between 120 K and 330 K by plane wave techniques. Additionally, strong anomalies occur in the thermal expansion between 310 K and 270 K which is also recognized by differential scanning calorimetry. The complete piezoelastic tensor was measured between 1 and 1600 bar under hydrostatic conditions.

The crystal structure of Ph 3 Pb(S 2 COMe) ( 1 ) features a tetrahedrally coordinated lead centre existing within a distorted tetrahedral geometry defined by three ipso-carbon atoms and a sulphur atom derived from a monodentate xanthate ligand. The xanthate ligand is orientated to place the oxygen atom in close proximity to the lead atom rather than the formally thione-sulphur atom. The structure of Ph 3 Pb(S 2 CO-i-Pr) ( 2 ) comprises three independent molecules that differ from each other only in the relative orientations of the lead-bound phenyl groups, the distorted tetrahedral coordination geometries and orientation of the xanthate ligand resembles that observed in ( 1 ). Globally, the crystal structures are similar in that they both comprise supramolecular layers of molecules self-assembled through C—H … π(aryl) contacts. Crystal data for ( 1 ): monoclinic, Cc , a = 17.614(4), b = 8.4270(18), c = 15.392(4) Å, β = 120.351(3)°, V = 1971.5(8) Å 3 , Z = 4, R = 0.028. Crystal data for ( 2 ): triclinic, P -1, a = 10.0922(11), b = 12.1182(12), c = 26.815(3) Å, α = 91.741(9), β = 96.406(9), γ = 96.768(9)°, V = 3233.1(6) Å 3 , Z = 6, R = 0.037.

Four new acetylacetonato disubstituted dihydrazones that feature different arylene and specifically spaced diaryl units between the hydrazone groups leading to different molecular geometries have been synthesized and comparatively studied with regard to their crystal structures. All structures show intramolecular N—H···O interactions to yield two six-membered hydrogen bonded chelate rings in the molecule. Dependent on the molecular geometry, intermolecular hydrogen bonding or offset π···π stacking contacts involving the aryl and chelate rings dominate the packing structure.

The crystal structures of four 4-{3-(X-phenyl)perhydro-1,3-oxazolo[3,4- a ]pyridin-1-yl}-2,8-bis(trifluoro-methyl)quinolines, ( 2 : X = H, 2-O 2 N, 3-O 2 N and 4-O 2 N) are reported. Differences in the conformations of the molecules are illustrated by the angles between the best planes through the various ring moieties. There are no strong intermolecular interactions, such as O—H···O, present in any of the four compounds. Instead, present in each of the four compounds are different combinations of some of C—H···F, C—H···O(nitro), C—H···π, C—F···π, N—O···π and π···π-stacking interactions, which result in very different supramolecular arrangements.