The two aromatic rings of the title compound, C(11)H(11)N(3)O, are nearly perpendicular to one another, with a dihedral angle between their planes of 80.52 (18)°. In the crystal, the amino N atom is a hydrogen-bond donor to the pyrazine N(1) atom of an inversion-related mol-ecule and the hy-droxy O atom is a hydrogen-bond donor to the pyrazine N(4) atom of another mol-ecule. The two hydrogen bo...

We present a microscopic model for metastable Si dangling-bond defect creation in hydrogenated amorphous silicon, which is applicable to both light-induced defect creation in solar cells ~Staebler-Wronski effect! and bias-stress-induced defect creation in thin-film transistors. Light or gate bias causes electron-hole pairs or electrons, respectively, to be localized on short, weak Si-Si bonds, ...

A typical volcano-shaped curve has been found in heterogeneous catalytic systems containing titanosilicates for the first time. A new reactive intermediate with double H-bonds is proposed. Systematic results clearly evidence another H-bond formed between the high-electronegativity atom of the H-bond acceptor and the H(end) atom of Ti-Oα-Oβ-H(end).

In the title compound, [Sn(C(7)H(7))(C(9)H(6)NO)(2)Cl], the Sn(IV) ion is in a distorted octa-hedral coordination environment formed by the O and N atoms of two bis-chelating quinolin-8-olate ligands, a Cl atom and a C atom from a benzyl ligand. The axial sites are occupied by an N atom of a quinolinate ligand and the C atom of the benzyl ligand. The axial Sn-N bond is slightly shorter than the...

The title compound, [ZnBr(C(9)H(6)NO)(C(9)H(7)NO)]·CH(3)OH, has its metal atom N,O-chelated by a neutral and a deproton-ated 8-hy-droxy-quinoline ligand. The hy-droxy unit of the neutral ligand is a hydrogen-bond donor to the methanol O atom and the alk-oxy O atom of the monoanionic ligand is a hydrogen-bond acceptor to the methanol O atom. In the crystal, adjacent mol-ecules are linked by thes...

In the title compound, C(12)H(10)N(2)O(4)S, the conformation of the N-H bond in the -SO(2)-NH- fragment is syn to the ortho-nitro group in the sulfonyl-benzene ring. The mol-ecule is twisted at the S-N bond, the C-N-S-C torsion angle being -72.83 (15)°. The dihedral angle between the benzene rings is 59.55 (7)°. The amide H atom and the nitro group O atom form an intra-molecular hydrogen bond, ...

The Sn atom in the title compound, [Sn(C(5)H(9))(C(6)H(5))(2)(C(6)H(10)N(3)O(2)S)], exists within a tetra-hedral geometry. The -NH(2) group forms a weak hydrogen bond across a center of inversion to the S atom of an adjacent mol-ecule, as well as another weaker hydrogen (across another center of inversion) to the Sn-bound O atom of another mol-ecule. The hydrogen-bonded layer structure is conso...

The reliability of four force fields developed for 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids are compared to an ab inito molecular dynamics simulation regarding structural properties. Except the hydrogen bond structure between the most acidic hydrogen atom of the imidazolium ring and the nitrogen atom of the anion as well as the intramolecular potential surface...

Let Tn denote the set of all unrooted and unlabeled trees with n vertices, and (i, j) a double-star. By assuming that every tree of Tn is equally likely, we show that the limiting distribution of the number of occurrences of the double-star (i, j) in Tn is normal. Based on this result, we obtain the asymptotic value of Randić index for trees. Fajtlowicz conjectured that for any connected graph ...