June 2000 issue
electronic papers (inorganic compounds)
The title structure was redetermined at 120 K, confirming the hydrogen-bond pattern found at room temperature, but showing the librational corrections of bond lengths to be unrealistic. The octahedral coordination of Mg atoms is slightly distorted due to hydrogen bonding.
electronic papers (metal-organic compounds)
The four title CuII compounds, namely [Cu(fpy)Cl]ClO4, [Cu(etpa)Cl][CuCl4]1/2, [Cu(mopy)Cl]ClO4 and [Cu(pipy)Cl]PF6, where fpy is (2-furylmethyl)bis(2-pyridylmethyl)amine, etpa is 2-[bis(2-pyridylmethyl)amino]ethanolate, mopy is (2-morpholinoethyl)bis(2-pyridylmethyl)amine and pipy is (2-piperidinylethyl)bis(2-pyridylmethyl)amine, have potentially tetradentate tripodal ligands. In [Cu(fpy)Cl]ClO4 (shown opposite), the O atom of the furan moiety coordinates weakly to the Cu atom at a distance of 2.750 (3) Å.
The title compound crystallizes from light petroleum with two independent molecules in the asymmetric unit. In both molecules, one of the three benzyl ligands is η2-bonded to the Zr atom, indicated by the smallest Zr—CH2Ph angle and the consequently relatively short Zr⋯Cipso distance.
The structure of the cation in the title compound consists of the Cr atom bonded to the N atoms of the three 1,10-phenanthroline ligands, resulting in a distorted octahedral arrangement with the six Cr—N distances ranging from 2.040 (4) to 2.055 (4) Å. One of the perchlorate anions is disordered and is located around two special positions.
The title compound is a centrosymmetric dimer. The terephthalate moiety acts as a bridging ligand and the phenanthrolines as terminal ligands. The unique Cu atom is coordinated by two O and four N atoms in a distorted octahedral geometry, with Cu—O distances of 1.955 (2) and 2.815 (2) Å, and Cu—N distances of 2.008 (2)–2.216 (2) Å.
The isomorphous title compounds, (I
>) and (II >), respectively, are monomeric and show distorted octahedral coordination with the monodentate dicyanamide ligands in cis positions. In both molecules, the metal–N(phenanthroline) bonds trans to the dicyanamide ligands are significantly longer than the other two.
The Ru atom in the title complex shows an octahedral coordination and a trans arrangement of the triphenylphosphine ligands. The observed bond lengths indicate a quinone rather than a diamide form for the o-benzoquinone diimine ligand. The complex molecule, in a special position, has crystallographic twofold symmetry.
The Ru atom in the title complex shows an octahedral coordination. The Cl− ion and the acetonitrile molecule are in the same plane as the o-benzoquinone diimine ligand, and the triphenylphosphine ligands are trans. Bond distances for the benzoquinone diimine ring establish a quinone arrangement.
The title compound consists of a hexaaquacobalt(II) cation and 4-toluenesulfonate anions, with no direct coordination of the anion to cobalt. The Co atom, in an octahedral geometry, is on a centre of inversion. The supramolecular structure consists of parallel layers of cations and anions. The anions are arranged with their sulfonate groups directed towards the cation layer in an alternating fashion and form hydrogen bonds with the water molecules of the cation.
The title compound is photochromic. Comparison with related complexes indicates that complexation with tricarbonylchromium has only minor effects on the structure of the chromene.
electronic papers (organic compounds)
The X-ray structure determinations of the dihydrochloride monohydrate, (I
>), and the trihydrochloride, (II >), of 7-methyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene are reported. Protonation occurs at the secondary amine N atoms in (I >) and at all the three amine N atoms in (II >) to which the Cl− ions are linked via N—H⋯Cl hydrogen bonds.
Sulfonium salts are known as photo acid generators (PAG) and have found a wide range of uses in photo-optical applications. Comparing the cations in the title compounds, (I
>) and (II >), respectively, there is no significant effect of the methyl/phenyl substituents on the bonding characteristics of the central S atom. As expected, in both cations, the S—Ph bonds are somewhat shorter than the S—Me bonds and the interactions between cations and anions, in both crystal structures, are similar.
In the two title adducts, (I
>) and (II >), respectively, hydrogen bonds between the diammonium and carboxylate ions form a two-dimensional network parallel to the ab plane in (I >) and one-dimensional chains along the c axis in (II >). The cyclohexanediammonium ion in (II >) has a crystallographic twofold axis.
n-Butylammonium dihydrogen phosphate is ferroelastic. Ferroelastic switching is concomitant with the hopping of some H atoms involved in hydrogen bonds from donor to acceptor O atoms.
The title compound was found to exist as the endo–cis isomer with a pair of enantiomers in the asymmetric unit. The cyclohexene ring is folded about the methylene-to-CH(acetoxy) vector to give a boat conformation.