Latest documents http://publikationen.stub.uni-frankfurt.de/index/index/ Mon, 25 Jun 2012 15:07:47 +0200 Mon, 25 Jun 2012 15:07:47 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25289 The structure of the title compound, (C15H15N2O4)[AgI2], consists of an organic 4-[3-(isonicotino­yloxy)propoxycarbon­yl]pyridinium cation which has a gauche–gauche (O/C/C/C—O/C/C/C or GG’) conformation and lies on a twofold rotation axis, which passes through the central C atom of the aliphatic chain, and an inorganic [AgI2]− anion. In the complex anion, the Ag+ cation is bound to two I− anions in a linear geometry. The anion was modelled assuming disorder around a crystallographic inversion centre near the location of the Ag+ cation. The crystal packing is stabilized by a strong inter­molecular N—H[cdots, three dots, centered]N hydrogen bond, which links the cations into zigzag chains with graph-set notation C(16) running along the face diagonal of the ac plane. The N-bound H atom is disordered over two equally occupied symmetry-equivalent sites, so that the mol­ecule has a pyridinium ring at one end and a pyridine ring at the other. Javier Vallejos; Iván Brito; Alejandro Cárdenas; Michael Bolte; Matías López-Rodríguez article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25289 Mon, 25 Jun 2012 15:07:47 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21919 The title compound, C20H22O4S2, was synthesized by the reaction of 1,4-dibromo­butene with methyl thio­salicylate. The aliphatic segment of this ligand is in an all-trans conformation. The bridging chain, –S-(CH2)4-S–, is almost planar (r.m.s. deviation for all non-H atoms: 0.056 Å) and its mean plane forms dihedral angles of 16.60 (7) and 5.80 (2)° with the aromatic rings. In the crystal, the mol­ecules are linked by weak C—H ... O inter­actions into chains with graph-set notation C(14) along [0 0 1]. The crystal studied was a racemic twin, the ratio of the twin components being 0.27 (9):0.73 (9). Iván Brito; Alejandro Cárdenas; Joselyn Albanez; Michael Bolte; Matías López-Rodríguez article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21919 Mon, 20 Jun 2011 11:13:09 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21918 There are two independent mol­ecules in the asymmetric unit of the title compound, C19H24S2. In both mol­ecules, the aliphatic segment of the ligand is in an all-trans conformation: the –S–(CH2)5–S–bridging chain is almost planar (r.m.s. deviation for all non-H atoms = 0.0393 and 0.0796 Å in the two mol­ecules) and maximally extended. Their mean planes form dihedral angles of 4.08 (6)/20.47 (6) and 2.22 (6)/58.19 (6)° with the aromatic rings in the two mol­ecules. The crystal packing is purely governed by weak inter­molecular forces. Iván Brito; Alejandro Cárdenas; Joselyn Albanez; Michael Bolte; Matías López-Rodríguez article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21918 Mon, 20 Jun 2011 11:10:10 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21914 The title compound. C15H14N2O4, (I), has a gauche–gauche (O/C/C/C—O/C/C/C or GG) conformation and is a positional isomer of propane-1,3-diyl bis­(pyridine-3-carboxyl­ate), (II). The mol­ecule of (I) lies on a twofold rotation axis, which passes through the central C atom of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. There is excellent agreement of the geometric parameters of (I) and (II). The most obvious differences between them are the O/C/C/C—O/C/C/C torsion angles [56.6 (2)° in (I) and 174.0 (3)/70.2 (3)° in (II) for GG and TG conformations, respectively] and the dihedral angle between the planes of the aromatic rings [80.3 (10)° in (I) and 76.5 (3)° in (II)]. The crystal structure is stabilized by weak C—H ... N and C—H ... O hydrogen bonding. Iván Brito; Javier Vallejos; Michael Bolte; Matías López-Rodríguez; Alejandro Cárdenas article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21914 Mon, 20 Jun 2011 10:41:13 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21900 The title compound, C15H14N2O4, has a trans–gauche [O/C/C/C–O/C/C/C] (TG) conformation. The angle between the planes of aromatic rings is 76.4 (3)°. The crystal structure is stabilized by van der Waals inter­actions and C—H ... O hydrogen bonds. The crystal used was a non-merohedral twin with a fractional contribution of the minor component of 0.443 (5). Iván Brito; Javier Vallejos; Michael Bolte; Matías López-Rodríguez article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21900 Mon, 20 Jun 2011 09:47:40 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21881 In the title compound, C15H14N2O4, (I), the mol­ecule lies on a twofold rotation axis which passes through the central C atom of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. The structure is a monoclinic polymorph of the triclinic structure previously reported [Brito, Vallejos, Bolte & López-Rodríguez (2010). Acta Cryst. E66, o792], (II). The most obvious difference between them is the O/C/C/C—O/C/C/C torsion angle [58.2 (7)° in (I) and 173.4 (3)/70.2 (3)° in (II) for GG and TG conformations, respectively]. Another important difference is observed in the dihedral angle between the planes of the aromatic rings [86.49 (7)° for (I) and 76.4 (3)° for (II)]. The crystal structure features a weak pi–pi inter­action [centroid–centroid distance = 4.1397 (10)Å]; this latter kind of inter­action is not evident in the triclinic polymorph. Iván Brito; Javier Vallejos; Alejandro Cárdenas; Matías López-Rodríguez; Michael Bolte article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21881 Fri, 17 Jun 2011 16:01:39 +0200