Disodium μ-triethylenetetraaminehexa-acetato-bis[oxovanadate(IV)] hexahydrate

The crystals structure of the title heterometallic coordination compound, Na-2[(C18H24N4O12)(VO)(2)].6H(2)O, is built of Na+ cations, binuclear [C18H24N4O12(VO)(2)](2-) dianions and water molecules. The cations and anion occupy special positions at inversion centers. The V atom has an octahedral coordination environment formed by the vanadyl oxo atom [V=O 1.618 (3) Angstrom], two N [V - N 2.174 (4) and 2.289 (4) Angstrom] and three O atoms [V - O 1.993 (3), 1.998 (3) and 2.001 (3) Angstrom] of the amino-carboxylato group

Unified force law for granular impact cratering

Experiments on the low-speed impact of solid objects into granular media have been used both to mimic geophysical events and to probe the unusual nature of the granular state of matter. Observations have been interpreted in terms of conflicting stopping forces: product of powers of projectile depth and speed; linear in speed; constant, proportional to the initial impact speed; and proportional to depth. This is reminiscent of high-speed ballistics impact in the 19th and 20th centuries, when a plethora of empirical rules were proposed. To make progress, we developed a means to measure projectile dynamics with 100 nm and 20 us precision. For a 1-inch diameter steel sphere dropped from a wide range of heights into non-cohesive glass beads, we reproduce prior observations either as reasonable approximations or as limiting behaviours. Furthermore, we demonstrate that the interaction between projectile and medium can be decomposed into the sum of velocity-dependent inertial drag plus depth-dependent friction. Thus we achieve a unified description of low-speed impact phenomena and show that the complex response of granular materials to impact, while fundamentally different from that of liquids and solids, can be simply understood

Convergence from clusters to the bulk solid: an ab initio investigation of clusters NanCln (n=2-40)

The electronic structures of a series of sodium chloride clusters (NaCl)(n) (n = 2-40) cut out from the NaCl solid have been investigated by means of ab initio calculations. The calculation results demonstrated a good correlation of the topologic parameters N-d (the total amount of dangling bonds of a cut-out cluster) and beta (the average dangling bonds on each in-cluster atom) with the stability of clusters as well as an evident convergence from clusters to the bulk solid. Particularly, we found that the effective charges on the Cl anions are more site dependent than size dependent

Diaquaiminodiacetatonickel(II)

The iminodiacetate dianion in diaquaiminodiacetato-nickel(II), [Ni(C4H5NO4)(H2O)(2)], chelates to the Ni atom through two carboxyl O and one imino N atoms; the six-fold coordination coordination environment comprises these three atoms, the water molecules and the carbonyl O atom of an adjacent dianionic group. The dative Ni<--O linkage leads to the formation of a helical chain running along the a axis of the orthorhombic crystal; adjacent chains are held in a network motif by hydrogen bonds

Disodium bis(1,2,4,5-benzenetetracarboxylato)-dihydroxytetrazincate(II) pyrazine

The tetranuclear dianion of the title compound, Na-2[Zn-4(C10H2O8)(2)(OH)(2)] . C4H4N2, forms a network framework in which the Zn atom exists in a tetrahedral environment, as it is coordinated by the carboxyl O atoms belonging to three different (C10H2O8)(4-) anions as well as by the bridging OH group. Adjacent OH groups are linked together through the uncoordinated heterocycle, which lies on a site of 2/m symmetry. The octahedrally coordinated Na ion, which lies on a site of 2 symmetry, interacts with one O atom of the carboxyl group of two anions and with two O atoms of the ortho-carboxyl groups of two other anions

1,3-di-2-pyridylthiourea monohydrate

The title compound, C11H10N4S.H2O, displays an intramoleculear N-amido...N-pyridyl hydrogen bond [2.652 (2) Angstrom] that locks the thiourea unit and one pyridyl ring into coplanarity [dihedral angle 2.7 (1)degrees]. The second pyridyl ring is also coplanar with the thiourea unit [dihedral angle 2.9 (1)degrees]. Its attached N atom interacts with the lattice water molecule to form a helical hydrogen-bonded chain that runs parallel to the b axis of the orthorhombic unit cell; adjacent chains are linked into a layer-like architecture by another hydrogen bond between the water molecule and the double-bonded S atom

Tetraaqua-1,2,4,5-benzenetetracarboxylato(pyrazine)dicobalt(II) dihydrate

The Co(II) atom in polymeric {[Co-2(C10H2O8)(C4H4N2)(H2O)(4)].2H(2)O}(n) exists in an octahedral coordination environment defined by the two O atoms of a chelating carboxyl group, the O atom of a monodentate carboxyl group of another benzenetetracarboxylato unit, two water molecules and the N atom of the pyrazine. The tetraanionic ligand and the N-heterocycle are located on inversion centers. The layer structure is linked by hydrogen bonds into a network structure

Polymeric dihydroxydiphthalatotricobalt(II)

In the crystal structure of dihydroxydiphthalatotricobalt(II), [Co-3(C8H4O4)(2)(OH)(2)](n), two of the four independent Co atoms lie at special positions of site symmetry 2. The hydroxy groups link three Co atoms to form a pyramidal Co3O unit, and adjacent Co3O units are linked through the Co base atoms into a honeycomb layer motif. Each of the phthalate dianions uses the O atoms of one carboxyl group to bind to three Co atoms, the bonding mode giving rise to six-coordinate Co atoms

Polymeric tetraapua(1,2,4,5-benzenetetracarboxylato)(pyrazine)dinickel(II) dihydrate

The Ni atom in the title compound, {[Ni-2(C10H2O8)(C4H4N2)( H2O)(4)] . 2H(2)O}(n), exists in an octahedral NO5Ni coordination environment that is defined by the two O atoms of a chelating carboxyl group, the O atom of a monodentate carboxyl group belonging to another carboxylato tetraanion, two water molecules and the N atom of the N-heterocycle. The tetracarboxylato anion and the pyrazine molecule are each located on a center of inversion. The bonding pattern leads to the formation of a layer structure; the layers are linked into a three-dimensional network by extensive hydrogen bonds involving the water molecules and the O atoms of the anionic unit

5-amino-1,3-benzothiazole-2(3H)-thione

The two independent molecules of the title compound, C7H6N2S2, are linked by two secondary amino-thione hydrogen bonds [3.344 (3) and 3.376 (3) Angstrom] to form a flat pseudo-centrosymmetric dimer