Conformational aspects of polymorphs and phases of 2-propyl-1-benzimidazole.

This paper reports on the polymorphism of 2-propyl-1-benzimidazole (2PrBzIm) induced by temperature change. Upon heating, an irreversible reconstructive-type phase transition at = 384 K from the ordered form (222) to a new polymorph, form (), was observed. The structural transformation between forms and involves significant changes in the crystal packing, as well as a key conformational variation around the propyl chain of the molecule.

Ordered vacancy distribution in 2/1 mullite: a superspace model.

A mullite single crystal with composition AlSiO exhibiting sharp satellite reflections was investigated by means of X-ray diffraction. For the refinement of a superspace model in the superspace group Pbam(α0½)0ss different scale factors for main and satellite reflections were used in order to describe an ordered mullite structure embedded in a disordered polymorph. The ordered fraction of the mullite sample exhibits a completely ordered vacancy distribution and can be described as a block structure of vacancy blocks (VBs) that alternate with vacancy-free blocks (VFBs) along a and c.

Nanoporosity, Inclusion Chemistry, and Spin Crossover in Orthogonally Interlocked Two-Dimensional Metal-Organic Frameworks.

[Fe(tvp)2 (NCS)2 ] (1) (tvp=trans-(4,4'-vinylenedipyridine)) consists of two independent perpendicular stacks of mutually interpenetrated two-dimensional grids. This uncommon supramolecular conformation defines square-sectional nanochannels (diagonal≈2.2 nm) in which inclusion molecules are located.

Bridging, terminal, free, anti and gauche BPA ligands in a 1D hybrid organic-inorganic Mn(II)-cyanate system.

A hybrid organic-inorganic chain compound of the family Mn(II)-bpa-(NCO) is presented. It contains, unusually, five different dispositions for the bpa [1,2-bis(4-pyridyl)ethane] ligand. Water molecules and free bpa ligands occupy the voids of the structure.

Erratum: [Bis(2-pyrid-yl)amine-N,N'](nitrato-O,O')cobalt(II) nitrate. Corrigendum.

The chemical name and formula in the paper by Castillo, Luque, De la Pinta & Román [Acta Cryst. (2001), E57, m384-m386] is corrected.[This corrects the article DOI: 10.

Defective dicubane-like tetranuclear nickel(II) cyanate and azide nanoscale magnets.

Four tetrameric nickel(II) pseudohalide complexes have been synthesized and structurally, spectroscopically, and magnetically characterized. Compounds 1-3 are isostructural and exhibit the general formula [Ni(2)(dpk·OH)(dpk·CH(3)O)(L)(H(2)O)](2)A(2)·2H(2)O, where dpk = di-2-pyridylketone; L = N(3)(-), and A = ClO(4)(-) for 1, L = NCO(-) and A = ClO(4)(-) for 2, and L = NCO(-) and A = NO(3)(-) for 3. The formula for 4 is [Ni(4)(dpk·OH)(3) (dpk·CH(3)O)(2)(NCO)](BF(4))(2)·3H(2)O.

Structural analysis, spectroscopic, and magnetic properties of the 1D triple-bridged compounds [M(dca)2(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)2]dca·6H2O.

The family of compounds [Mn(dca)(2)(bpa)] (1), [Fe(dca)(2)(bpa)] (2), [Co(dca)(2)(bpa)] (3), [Zn(dca)(2)(bpa)] (4), and [Ni(dca)(bpa)(2)]dca·6H(2)O (5), with dca = dicyanamide and bpa = 1,2-bis(4-pyridyl)ethane, has been synthesized. These compounds have been characterized by single crystal (1, 2, 4, and 5) and powder X-ray diffraction (3), by Fourier transform infrared (FTIR), UV-vis, and electron paramagnetic resonance (EPR) spectroscopies, and by magnetic measurements. Compound 1 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.

Trinuclear nickel(II) complex through a 2,3,5,6-tetrakis(2-pyridyl)pyrazine ligand with a linear exchange pathway.

The compound [Ni(3)(tppz)(2)(NCS)(2)(H(2)O)(4)](NO(3))(4).4H(2)O [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine and NCS = thiocyanate ligand] consists of trimeric units, where the three Ni(II) cations are linked by two bis-tridentate tppz ligands. This compound crystallizes in the monoclinic space group C2/c, with Z = 4, a = 25.

Bis(2,3,5,6-tetra-2-pyridyl-pyrazine-κN,N,N)nickel(II) dithio-cyanate dihydrate.

In the title compound, [Ni(C(24)H(16)N(6))(2)](NCS)(2)·2H(2)O, the central Ni(II) ion is octahedrally coordinated by six N atoms of two tridentate 2,3,5,6-tetra-2-pyridyl-pyrazine ligands (tppz). Two thio-cyanate anions act as counter-ions and two water mol-ecules act as solvation agents. O-H⋯N hydrogen bonds are observed in the crystral structure.

Aqua-(dicyanamido-κN)(nitrato-κO,O')(2,3,5,6-tetra-2-pyridylpyrazine-κN,N,N)manganese(II).

In the title compound, [Mn(C(2)N(3))(NO(3))(C(24)H(16)N(6))(H(2)O)], the central manganese(II) ion is hepta-coordinated to a tridentate 2,3,5,6-tetra-2-pyridylpyrazine ligand (tppz), a bidentate nitrate ligand, a terminal monodentate dicyanamide ligand (dca) and a water mol-ecule. The structure contains isolated neutral complexes, which are linked by O(water)-H⋯N hydrogen bonds generating chains along [010].