μ-Methylene-bis[dibromido(diethyl ether-κO)aluminium(III)]: crystal structure and chemical exchange in solution

In the title compound, [Al2Br4(CH2)(C4H10O)2], the molecule lies on a crystallographic twofold axis passing through the bridging C atom. Each AlIII atom is four-coordinate, being bonded to two bromide ions, bridging the CH2 group as well as the oxygen atom of a diethyl ether ligand in a slightly distorted tetrahedral arrangement with angles ranging from 101.52 (8) to 116.44 (5)°. The Al—CH2—Al angle, 118.4 (2)°, is the smallest observed for a structure where this moiety is not part of a ring. In the crystal, weak C—H...Br interactions, characterized as R 2 2(12) rings, link the molecules into ribbons in the [101] direction. The title compound is monomeric and coordinatively saturated in the solid state, as each aluminum is four-coordinate, but in solution the ether molecules from either or both Al atoms can dissociate, and would be expected to rapidly exchange, and this is supported by NMR data.

catena-Poly[[(2,2′-bipyridine-κ2 N,N′)manganese(II)]-di-μ-bromido]

In the polymeric title complex, [MnBr2(C10H8N2)] n , the MnII ion, situated on a twofold axis of symmetry, is six-coordinated in a distorted octahedral coordination geometry defined by two N atoms from the chelating 2,2′-bipyridine ligand and four bridging Br− anions. The crystal reveals a one-dimensional Br-bridged chain along the c-axis direction with a zigzag topology. In the crystals, contacts between chains include π–π interactions between pyridyl rings [inter-centroid separation = 4.082 (1) Å]

Crystal structure of the unusual coordination polymer catena-poly[[gold(I)-μ-1,2-bis(diphenylphosphinothioyl)ethane-κ2 S:S′] dibromidoaurate(I)]

In the title compound, {[Au(C26H24P2S2)][AuBr2]} n , the gold(I) centres of the cation are coordinated by the P=S groups of the disulfide ligands to form a chain polymer parallel to the c axis. Both independent gold atoms lie on the same twofold axis, and the midpoint of the H2C—CH2 bond lies on an inversion centre. The anions flank the polymeric chain; they are connected to it by short aurophilic interactions and C—H...Br contacts, and to each other by Br...Br contacts.

Crystal structures of alpha and beta modifications of Mn as packing of tetrahedral helices extracted from a four-dimensional {3, 3, 5} polytope

The crystal structures of both α- and β-Mn modifications have been presented as packing of tetrahedral helices extracted from four-dimensional {3, 3, 5} polytope construction. Presentation of the β-Mn structure as a primitive cubic arrangement formed by double tetrahedral helices around a central tetrahedral Coxeter–Boerdijk helix (tetrahelix) enables the inclusion in the structure description not only all atoms but also all tetrahedra; these tetrahedra are not accounted for in the preceding models for the β-Mn structure. The tetrahelix periodicity arising by minimal deformations of tetrahedra edges is equal to eight tetrahedra and coinciding with the lattice periods of both modifications. The linear substructure of α-Mn crystal consists of four tetrahelices which join to each other by edges around the common twofold axis. The α-Mn structure has been presented as primitive cubic arrangement constructed from such rods.

Polymorphism of bis(1,3-benzothiazol-2-yl) trithiocarbonate

The polymorphism of the title compound, C15H8N2S5, is reported, in which the (syn,syn) and (syn,anti) conformers simultaneously crystallized from a chloroform solution. The complete molecule of the (syn,syn) form is generated by a crystallographic twofold axis. The geometries of both conformers are compared in detail, revealing no significant differences in bond lengths, despite different bond angles because of the conformational changes. Analysis of the intermolecular interactions, aided by Hirshfeld surfaces, shows distinctive S...S and S...N contacts only for the (syn,anti) conformer. Aromatic π–π-stacking interactions are found for both conformers, which occur for the (syn,anti) conformer between pairs of molecules, but are continuous stacks in the (syn,syn) conformer. Non merohedral twinning was found for the crystal of the (syn,anti) conformer used for data collection.

Crystal structures of a series of bis(acetylacetonato)oxovanadium(IV) complexes containing N-donor pyridyl ligands

Crystal structures for a series of bis(acetylacetonato)oxovanadium(IV) complexes containing N-donor pyridyl ligands are reported, namely, bis(acetylacetonato-κ2 O,O′)oxido(pyridine-κN)vanadium(IV), [V(C5H7O2)2O(C5H5N)], 1, bis(acetylacetonato-κ2 O,O′)oxido(pyridine-4-carbonitrile-κN)vanadium(IV), [V(C5H7O2)2O(C6H4N2)], 2, and bis(acetylacetonato-κ2 O,O′)(4-methoxypyridine-κN)oxidovanadium(IV), [V(C5H7O2)2O(C6H7NO)], 3, Compounds 1–3 have the formulae VO(C5H7O2)2 L, where L = pyridine (1), 4-cyano-pyridine (2), and 4-methoxypyridine (3). Compound 1 was previously reported [Meicheng et al. (1984). Kexue Tongbao, 29, 759–764 and DaSilva, Spiazzi, Bortolotto & Burrow (2007). Acta Crystallogr., E63, m2422] and redetermined here at cryogenic temperatures. Compounds 1 and 2 as pyridine and 4-cyanopyridine adducts, respectively, crystallize as distorted octahedral structures with the oxo and pyridyl ligands trans to one another. A crystallographic twofold axis runs through the O—V—N bonds. Compound 3 containing a 4-methoxypyridine ligand crystallizes as a distorted octahedral structure with the oxo and pyridyl ligands cis to one other, removing the twofold symmetry seen in the other complexes.

An unusually short intermolecular N—H...N hydrogen bond in crystals of the hemi-hydrochloride salt of 1-exo-acetamidopyrrolizidine

The title compound [systematic name: (1R*, 8S)-2-acetamidooctahydropyrrolizin-4-ium chloride–N-[(1R, 8S)-hexahydro-1H-pyrrolizin-2-yl)acetamide (1/1)], 2(C9H16N2O)·HCl or C9H17N2O+·Cl−·C9H16N2O, arose as an unexpected product when 1-exo-acetamidopyrrolizidine (AcAP; C9H16N2O) was dissolved in CHCl3. Within the AcAP pyrrolizidine group, the unsubstituted five-membered ring is disordered over two orientations in a 0.897 (5):0.103 (5) ratio. Two AcAP molecules related by a crystallographic twofold axis link to H+ and Cl− ions lying on the rotation axis, thereby forming N—H...N and N—H...Cl...H—N hydrogen bonds. The first of these has an unusually short N...N separation of 2.616 (2) Å: refinement of different models against the present data set could not distinguish between a symmetrical hydrogen bond (H atom lying on the twofold axis and equidistant from the N atoms) or static or dynamic disorder models (i.e. N—H...N + N...H—N). Computational studies suggest that the disorder model is slightly more stable, but the energy difference is very small.

Sodium [N,N′-ethylenebis(D-penicillaminato)]indate(III) tetrahydrate

The asymmetric unit of the title compound {systematic name: sodium [2-({2-[(1-carboxylato-2-methyl-2-sulfanidylpropyl)amino]ethyl}amino)-3-methyl-3-sulfanidylbutanoato-κ4 S,N,N′,S′]indate(III) tetrahydrate}, Na[In(C12H20N2O4S2)]·4H2O, contains four indate(III) complex anions {[In(D-ebp)]−; D-H4ebp = N,N′-ethyelenebis(D-penicillamine)], four sodium(I) cations and sixteen water molecules. The indate(III) anions and sodium cations are alternately connected through coordination bonds between Na+ ions and the carboxylate groups of the complex anions, forming an infinite sixfold right-handed helix along the c-axis direction. In the crystal, the helices are linked by O—H...O hydrogen bonds between water molecules bound to Na+ ions and carboxylate groups. The crystal studied was twinned via a twofold axis about [001].

(μ-Di-tert-butylsilanediolato)bis[bis(η5-cyclopentadienyl)methylzirconium]

The reaction of t-Bu2Si(OH)2 with two equivalents of Cp2Zr(CH3)2 produces the title t-Bu2SiO2-siloxide bridged dimer, [Zr2(CH3)2(C5H5)4(C8H18O2Si)] or [Cp2Zr(CH3)]2[μ-t-Bu2SiO2] (1), where one methyl group is retained per zirconium atom. The same product is obtained at room temperature even when equimolar ratios of the silanediol and Cp2Zr(CH3)2 are used. Attempts to thermally eliminate methane and produce a bridging methylene complex resulted in decomposition. The crystal structure of 1 displays typical Zr—CH3 and Zr—O distances but the Si—O distance [1.628 (2) Å] and O—Si—O angle [110.86 (15)°] are among the largest observed in this family of compounds suggesting steric crowding between the t-Bu substituents of the silicon atom and the cyclopentadienyl groups. The silicon atom lies on a crystallographic twofold axis and both Cp rings are disordered over two orientations of equal occupancy.

(1Z,2Z)-1,2-Bis{2-[3,5-bis(trifluoromethyl)phenyl]hydrazinylidene}-1,2-bis(4-methoxyphenyl)ethane including an unknown solvate

The complete molecule of the title compound, C32H22F12N4O2, is generated by a crystallographic twofold axis aligned parallel to [010]. The F atoms of one of the CF3 groups are disordered over three orientations in a 0.6: 0.2: 0.2 ratio. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming zigzag chains propagating along the a-axis direction. In addition, weak C—H...O and C—H...F bonds are observed. The contribution of the disordered solvent to the scattering was removed using the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] of PLATON. The solvent contribution is not included in the reported molecular weight and density.