October 1999 issue
cif-access (inorganic compounds)
Potassium zinc hydrogenphosphate dihydrogenphosphate hy- drate, KZn(HPO4)(H2PO4) f vertex-sharing ZnO4 and PO4 groups. It is isostructural with NH4Zn(HPO4)(H2PO4).H2O and RbZn(HPO4)(H2PO4).H2O.
Disodium zinc tetrakis(dihydrogenphosphate) tetrahydrate, Na2Zn(H2PO4)4.4H2O, is built up from vertex-sharing octahedral NaO6 and ZnO6, and tetrahedral PO4 building blocks. It is isostructural with Na2Ni(H2PO4)2.4H2O.
cif-access (metal-organic compounds)
The title compound is a rare example of a crystallographically characterized twofold chloro-bridged dirhenium complex. The molecule shows a planar Re2Cl2 ring with Re—Cl bond lengths of 2.5316(12) and 2.5404(11)Å. The two dicyclohexylphosphine ligands attached to the Re atoms are in anti positions.
In the cluster anion, composed of six AgI atoms and 11 iodides, the Ag6 core forms a trigonal prism. Each AgI atom has a distorted tetrahedral geometry. The average Ag⋯Ag and Ag—I distances are 3.2005 (14) and 2.9377 (9) Å, respectively.
The title compound contains two acetonitrile and 2,2'-bipyridine molecules in the equatorial plane. Two mutually trans-positioned chloride ligands occupy the axial positions in an almost linear arrangement. A substantial number of intermolecular hydrogen-bond interactions mediated by a solvate water and several neighboring molecules are observed.
The Fe atom lies on an inversion center with a distorted octahedral coordination geometry defined by two pyridine N atoms and four water O atoms. The crystal structure is stabilized by O—H⋯O hydrogen bonds involving all the water H atoms and the carboxylate groups.
In [(C5H5FeC5H4)2(C5H4S5)], the values of the geometric parameters of the ferrocene and 1,3-dithiole-2-thione (dmit) moieties are within the normal ranges. There is an unusual thiol-S atom short contact [3.4889(18)Å] to a thione-S atom.
cif-access (organic compounds)
The aliphatic chains of the title molecules, C12H20N2OS, (I), and C13H22N2OS, (II), align themselves parallel in the (101) crystallographic plane in both crystal structures.
The title compound, 1,4,9,12-tetraoxacyclohexadeca-6,14-diene-5,8,13,16-tetraone, a cyclic dimer, was prepared using dilute-solution ring-chain trans-esterification reactions. The molecule has crystallographic twofold rotation symmetry and contains four ester groups linked by two planar ethylene and two staggered ethane units.
The title compound is an enynoate bearing a protected amino group at the olefinic C atom next to the ester group. The amino group is protected with a benzyl and a benzyloxycarbonyl group. The compound belongs to the group of acetylenic Michael acceptors which react with organocuprate reagents in a 1,6-Michael addition to functionalized allenes. Bearing a protected amino group, the title compound could be a precursor in the synthesis of allenic α-amino acids.
The title compound is a derivative of the major cycloaddition product of dimethyl fumarate and 3-methyl-(E)-2,4-pentadiene-1-ol. The structure determined confirms that the major cycloadduct arises from the expected endo transition state.
In 3',4'-dihydro-2',2,4,5-tetraphenylspiro[pyrazolidine-3,3'-(2H-1-benzopyran)]-4'-one, the pyrazolidine ring adopts an envelope conformation and the six-membered ring in the flavanone moiety adopts a sofa conformation. The spiro substitution of the pyrazolidine ring causes elongation of the bonds within the flavanone moiety.
In the title compound, the pyridine ring is planar. The central ring adopts a skew boat conformation where the methoxy carbonyl group is attached axially and the hydroxyl is attached equatorially. An O—H⋯N hydrogen bond links the molecules into infinite chains.
The title compound is one in a series of new bidentate aminoindenyl ligands synthesized during the course of our studies on transition metal complexes bearing chelating indenyl ligands. We studied this compound in order to compare its parameters with those found in complexes wherein the indene and/or amine moieties are coordinated to a transition metal.
The structure of the title compound was determined at 133K to establish the absolute configuration of the chiral centers. The pyrrolidine ring has an envelope conformation. The molecule is stabilized by a weak bifurcated intramolecular hydrogen bond. The crystal packing consists of intermolecular O—H⋯O and C—H⋯O hydrogen bonds.
The structures of (I) and (II) were determined at 134 K. The pyrrolidine rings have similar twist conformations in both compounds. Molecules of (II) are connected through intermolecular N—H⋯O hydrogen bonds into zigzag chains. Both crystal structures contain weak intermolecular C—H⋯O interactions. Compound (II) also shows intermolecular C—H⋯πarene interactions.
In the title compounds, the cation distributions correspond to a normal garnet structure for Ca3Fe2Ge3O12 and Ca3Y2Ge3O12, and to an inverse garnet structure for (MgY2)Mg2Ge3O12.
The title one-dimensionally extended chain aluminophosphate, ethylenediammonium bis(propane-1,3-diyldiammonium) dialuminium tetraphosphate, [NH3(CH2)2NH3][NH3(CH2)3NH3]2[Al2P4O16], contains infinite [AlP2O8]3- chains composed of AlO4 and PO2(=O)2 tetrahedra, held together via hydrogen bonds by two kinds of protonated amines.