Search

This paper reports the hydrothermal synthesis and crystal structure refinement of diiron(II) phosphate hydroxide, FeII2(PO4)(OH), obtained at 1063 K and 2.5 GPa. This phosphate is the synthetic analogue of the mineral wolfeite, and has a crystal structure topologically identical to those of minerals of the triplite–triploidite group. The complex framework contains edge- and corner-sharing FeO4(OH) and FeO4(OH)2 polyhedra, linked via corner-sharing to the PO4 tetrahedra (average P—O distances are between 1.537 and 1.544 Å). Four five-coordinated Fe sites are at the centers of distorted trigonal bipyramids (average Fe—O distances are between 2.070 and 2.105 Å), whereas the coordination environments of the remaining Fe sites are distorted octahedra (average Fe—O distances are between 2.146 and 2.180 Å). The Fe—O distances are similar to those observed in natural Mg-rich wolfeite, except for two Fe—O bond distances, which are significantly longer in synthetic Fe2+2(PO4)(OH). [ABSTRACT FROM AUTHOR]

Molecules of the title compound, C12H13NO3, are not planar and are stabilized by electrostatic interactions, as the dipole moment of the molecule is 3.76 D. They are also stabilized by intramolecular hydrogen bonds of N...O and C...O types, and by a complicated network of weak intermolecular hydrogen bonds of the C...O type. This paper also reports the theoretical investigation of the hydrogen bonding and electronic structure of the title compound using natural bond orbital (NBO) analysis. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, C23H22BrN3, a strong conjugation of the pyrazoline chromophore with the aromatic rings at positions 1 and 3 is observed, as well as a significant shift in the synclinal→synperiplanar direction. The absolute structure was unequivocally determined. In the absence of clasical hydrogen-bond donors, the structure is stabilized by weak C—H...π interactions. This paper also reports the electronic structure of the title compound using NBO (natural bond order) analysis. The contributions of lone pairs to the relevant bonds were revealed. [ABSTRACT FROM AUTHOR]

Crystal structures are reported for three isomeric compounds, namely 2-(2-hydroxy­phenyl)-2-oxazoline, (I), 2-(3-hydroxy­phenyl)-2-oxazoline, (II), and 2-(4-hydroxy­phenyl)-2-oxazoline, (III), all C9H9NO2 [systematic names: 2-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (I), 3-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (II), and 4-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (III)]. In these compounds, the deviation from coplanarity of the oxazoline and benzene rings is dependent on the position of the hydroxy group on the benzene ring. The coplanar arrangement in (I) is stabilized by a strong intra­molecular O—H⋯N hydrogen bond. Surprisingly, the 2-oxazoline ring in mol­ecule B of (II) adopts a 3 T4 (C2 TC3) conformation, while the 2-oxazoline ring in mol­ecule A, as well as that in (I) and (III), is nearly planar, as expected. Tetra­mers of mol­ecules of (II) are formed and they are bound together via weak C—H⋯N hydrogen bonds. In (III), strong inter­molecular O—H⋯N hydrogen bonds and weak intra­molecular C—H⋯O hydrogen bonds lead to the formation of an infinite chain of mol­ecules perpendicular to the b direction. This paper also reports a theoretical investigation of hydrogen bonds, based on density functional theory (DFT) employing periodic boundary conditions. [ABSTRACT FROM AUTHOR]

Editorial. Reveals the changes to the Section C of the periodical 'Acta Crystallographica.' Streamlining of submission processes for the section; Revision of the checking process.

To address the question of the role of chirality at the metal in enantioselective catalysis, a pseudo-tetrahedral three-legged piano-stool complex has been prepared, i.e. [RuCl(C26H27N2P)](CF3SO3). Anchoring a phosphine and a pyrazole tether to an arene (PArN) yields, after η6:η1:η1 coordination to ruthenium, [{η6:η1:η1-(PArN)}RuCl]+ as a 1:1 mixture of enantiomers. Unfortunately, all attempts to resolve the enantiomers failed. The structure solution revealed the presence of racemic crystals. [ABSTRACT FROM AUTHOR]

In the title compound, C19H20O8, the benzene rings are nearly perpendicular to each other [dihedral angle 80.2 (2)°]. The carboxy group is twisted out while both the methoxy and acetyl groups are almost coplanar with their attached benzene rings. The hydroxy group is involved in an intramolecular O-H⃛O hydrogen bond with the acetyl O atom and the compound is connected through an intermolecular O-H⃛O contact to form a dimer. The crystal structure is stabilized by intermolecular O-H⃛O hydrogen bonds. [ABSTRACT FROM AUTHOR]

During an investigation of the W/Te/Br2 system, we prepared crystals of the title compound, C20H40N4S8Te, from aceto­nitrile solution by slow addition of diethyl ether. It appeared to be a new tetragonal modification. The calculated density of the tetragonal modification (1.513 Mg m−3) is slightly greater than found for the known orthorhombic modification (1.46 Mg m−3). The bond distances and angles are practically the same. [ABSTRACT FROM AUTHOR]

The structure of the synthetic protected dipeptide ( Z)-Pro-Leuol [systematic name: benzyl 2-(1-hydroxy­methyl-3-methyl­butyl­amino­carbonyl)­pyrrolidine-1-carboxyl­ate], C19H28N2O4, was determined by X-ray crystallography. The peptide adopts a novel backbone conformation compared with other longer oligopeptides containing Pro-Leuol. [ABSTRACT FROM AUTHOR]

The previously unknown title compound, tetra-μ-ace­tato-1:2κ2 O;1:2κ2 O: O′;­2:3κ2 O;­2:3κ2 O: O′-di­aqua-1κ O,3κ O-bis­(μ-2-{[ N-ethyl- N-(2-hy­droxy-5-methylbenzyl)­am­ino]­methyl}-1-methyl-1 H-benz­imid­az­ole)-1κ3 N3, N, O:2κ O;3κ3 N3, N, O:2κ O-tri­nickel(II) tetra­hy­drate, [Ni3(C18H22N3O)2(C2H3O2)4(H2O)2]·­4H2O, (I), is a centrosymmetric linear trinuclear nickel(II) complex, where the Ni atoms are in an octahedral coordination and the ligand heteroatoms act so as to model amino acid residues. [ABSTRACT FROM AUTHOR]

Amido complexes of titanium are useful reagents in a variety of syntheses and as precursors for chemical vapour deposition of TiN. The title compound, di­chloro­bis­(di­methyl­amido)(di­methyl­amine)­titanium(IV), [TiCl2(C2H6N)2(C2H7N)], crystallizes with one mol­ecule in the asymmetric unit. The neutral complex shows an unusual fivefold coordination of the titanium centre with a distorted trigonal-bipyramidal geometry and the di­methyl­amine mol­ecule occupying an axial position. [ABSTRACT FROM AUTHOR]

In the title compounds, C23H33NO3 and C21H30O3, respectively, the ester linkage in ring A is equatorial. In these steroids, the six-membered rings A and B have chair conformations, but ring C can be better described as a half-chair. The five-membered ring D adopts a 14α-envelop conformation. The A/ B, B/ C and C/ D ring junctions are trans. [ABSTRACT FROM AUTHOR]