Tricarbonylchlorido(6'7'-dihydro-5’H-spiro[cyclopentane-1,6'-dipyrido-[3,2-d:2',3'-f][1,3]diazepine]-κ2N1,N11)-rhenium(I)

In the title compound, [ReCl(C15H16N4)(CO)3], the ReI ion is coordinated in a distorted octahedral geometry by one Cl atom, two N atoms of the bidentate ligand and three carbonyl groups. The cyclopentane group is orientated in a transoid fashion with respect to the chloride ligand. The dihedral angle between the pryridine rings is 10.91 (12)°. In the crystal, N-H...Cl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (001)

Tricarbonylchlorido(6’,7’-dihydro-5’H-spiro[cyclohexane-1,6’-dipyrido[3,2-d :2’,3’-f][1,3]diazepine]-κ2N1,N11)rhenium(I)

In the title compound, [ReCl(C16H18N4)(CO)3], the ReI ion is coordinated in a distorted octahedral geometry by one Cl atom, two N atoms of the bidentate ligand and three carbonyl groups. The cyclohexane group is orientated in a transoid fashion with respect to the chloride ligand. In the crystal, N-H...Cl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (100)

NaV2O4: a Quasi-1D Metallic Antiferromagnet with Half-Metallic Chains

NaV2O4 crystals were grown under high pressure using a NaCl flux, and the crystals were characterized with X-ray diffraction, electrical resistivity, heat capacity, and magnetization. The structure of NaV2O4 consists of double chains of edge-sharing VO6 octahedra. The resistivity is highly anisotropic, with the resistivity perpendicular to the chains more than 20 times greater than that parallel to the chains. Magnetically, the intrachain interactions are ferromagnetic and the interchain interactions are antiferromagnetic; 3D antiferromagnetic order is established at 140 K. First principles electronic structure calculations indicate that the chains are half metallic. Interestingly, the case of NaV2O4 seems to be a quasi-1D analogue of what was found for half-metallic materials.Comment: 14 pages, including 4 figures and 1 table, accepted for publication in PR

Bis[5-oxo-4,5-dihydro-8H-2-azonia-4,8,9-trizabicyclo[4.3.0]nona-2,6,9(1)-triene] sulfate

In the crystal structure of the title compound, 2C5H5N4O+·SO4 2−, N—H⋯O hydrogen bonds assemble the mol­ecules into a two-dimensional network structure parallel to the cb plane. The S atom of the sulfate ion lies on a special position on a twofold axis

Substitutional disorder in the ionic diorganoanti­mony halide adduct [bromido/chlorido(0.33/0.67)][2-(di­methyl­amino­meth­yl)phen­yl][2-(di­methyl­ammonio­meth­yl)phen­yl]anti­mony(III) 0.75-bromide 0.25-chloride

The title complex, [SbBr0.33Cl0.67(C9H13N)(C9H12N)]Br0.75Cl0.25, exhibits substitutional disorder of both halogen atoms in the asymmetric unit, however, with different occupancies. Thus, the halogen atom bonded to Sb has 0.67 (4) occupancy for Cl and 0.33 (4) for Br, while the anionic halogen atom shows 0.75 (4) occupancy for Br and 0.25 (4) for Cl. An N—H⋯Cl/Br hydrogen bond is established between the cation and the halide anion. The coordination geometry of the Sb center in the cation is distorted pseudo-trigonal-bipyramidal as a result of the strong intra­molecular N→Sb coordination trans to the Sb—Cl/Br bond. The pendant arm on the second ligand is twisted away from the metal center. The compound crystallizes as a racemate, i.e. a mixture of (R N2,C Sb1) and (S N2,A Sb1) isomers with respect to planar chirality induced by the coordinating N atom and chelate-induced Sb chirality. These isomers are associated through Cphen­yl—H⋯Cl/Br hydrogen bonds, forming a three-dimensional architecture

CRYSTAL AND MOLECULAR-STRUCTURE OF 2',3',5'-TRI-O-ACETYL-6-O-(MESITYLENESULPHONYL)GUANOSINE

The structure of a 6-O-mesitylenesulphonyl derivative of 2',3',5'-tri-O-acetylguanosine, C 24 H 29 N50 10 S, has been determined by X-ray diffraction. Crystals are monoclinic, a = 26.370 (4), b = 8.200 (2), c = 17.991 (3) A, fl = 132.77 (4) o. The solution of the structure in space group C2 was not straightforward and is described in detail. Refinement converged at R = 0.110 for 1102 observed reflections. The guanine base displays some deviations from its usual geometry due to the loss of C(6)-O(6) double-bond character. The ribose sugar is C(2')-endo puckered

4-Hydr­oxy-4,4-diphenyl­butan-2-one

The mol­ecules of the title compound, C16H16O2, display an intra­molecular O—H⋯O hydrogen bond between the hydroxyl donor and the ketone acceptor. Inter­molecular C—H⋯π inter­actions connect adjacent mol­ecules into chains that propagate parallel to the ac diagonal. The chains are arranged in sheets, and mol­ecules in adjacent sheets inter­act via inter­molecular O—H⋯O hydrogen bonds

THEORETICAL STUDIES OF BILIPROTEIN CHROMOPHORES AND RELATED BILE PIGMENTS BY MOLECULAR ORBITAL AND RAMACHANDRAN TYPE CALCULATIONS

Ramachandran calculations have been used to gain insight into steric hindrance in bile pigments related to biliprotein chromophores. The high optical activity of denatured phycocyanin, as compared to phycoerythrin, has been related to the asymmetric substitution at ring A, which shifts the equilibrium towards the P-helical form of the chromophore. Geometric effects on the electronic structures and transitions have then been studied by molecular orbital calculations for several conjugation systems including the chromophores of phycocyanin. phytochrome P,, cations, cation radicals and tautomeric forms. For these different chromophores some general trends can be deduced. For instance, for a given change in the gross shape (e.g. either unfolding of the molecule from a cyclic-helical to a fully extended geometry, or upon out-of-plane twists of the pyrrole ring A) of the molecules under study, the predicted absorption spectra all change in a simikar way. Nonetheless, there are characteristic distinctions between the different n-systems, both in the transition energies and the charge distribution, which can be related to their known differences in spectroscopic properties and their reactivity

1-Methyl-2,6-cis-distyrylpiperidine

The complete molecule of the title compound, C22H25N, is generated by crystallographic mirror symmetry, with two C atoms and the N atom lying on the mirror plane. The central ring adopts a chair conformation and the dihedral angle between the aromatic rings is 56.69 (4)°

{Tris[2-(imidazol-2-ylmethyl­imino)eth­yl]methyl­ammonium}iron(II) tris­(per­chlorate) dihydrate

The title complex, [Fe(C19H27N10)](ClO4)3·2H2O, is a new polymorph of an iron(II) Schiff base complex of tris­(2-amino­ethyl)methyl­ammonium with imidazole-2-carboxaldehyde. The octa­hedral FeII atom is bound to three facial imidazole N atoms with average Fe—Nimidazole and Fe—Nimine bond distances of 1.963 (5) and 1.951 (5) Å, respectively. The central N atom of the tripodal ligand is outside the bonding distance at 3.92 Å. The crystal packing is stabilized by the hydrogen-bonding inter­actions between the two water mol­ecules (acceptor) and two of the three imidazole NH groups (donor). The third imidazole NH group (donor) forms a hydrogen bond to one of the three perchlorate counter-ions (acceptor)