Latest documents http://publikationen.stub.uni-frankfurt.de/index/index/ Tue, 28 Aug 2012 09:19:27 +0200 Tue, 28 Aug 2012 09:19:27 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25859 Mol­ecules of the title compound (alternative name: butane-1,4-diyl dinicotinate), C16H16N2O4, lie on a inversion centre, located at the mid-point of the central C—C bond of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. The butane chain adopts an all-trans conformation. The dihedral angle between the mean plane of the butane-3-carboxyl­ate group [for the non-H atoms, maximum deviation = 0.0871 (15) Å] and the pyridine ring is 10.83 (7)°. In the crystal, mol­ecules lie in planes parallel to (122). The structure features weak π–π inter­actions with a centroid–centroid distance of 3.9281 (11) Å. Javier Vallejos; Iván Brito; Alejandro Cárdenas; Michael Bolte article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25859 Tue, 28 Aug 2012 09:19:27 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25302 The title compound, C14H20O5S·0.5H2O, crystallizes with two organic mol­ecules and a solvent water mol­ecule in the asymmetric unit. In both mol­ecules, the hexa­pyranosyl rings adopt a slightly distorted chair conformation (5 C 2) with four substituents in equatorial positions and one substituent in an axial position. The main difference between the organic mol­ecules is the dihedral angle between the phenyl ring and the best plane defined by the O—C1—C2—C3 atoms (r.m.s deviations = 0.003 and 0.043 Å) of the hexa­pyranosyl rings [47.4 (4) and 86.5 (4)°]. In the asymmetric unit, mol­ecules are linked by two strong O—H[cdots, three dots, centered]O hydrogen bonds. In the crystal, the components are linked by a total of 10 distinct O—H[cdots, three dots, centered]O hydrogen bonds, resulting in the formation of a two-dimensional network parallel to the ab plane. Iván Brito; László Szilágyi ; Ambati Ashok Kumar; Joselyn Albanez; Michael Bolte article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25302 Wed, 27 Jun 2012 12:35:24 +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/25270 In the title compound, [Ag(BF4)(C14H12N2O4)]n, the coordination of the Ag+ ion is trigonal–bipyramidal with the N atoms of two ethane-1,2-diyl bis­(pyridine-3-carboxyl­ate) ligands in the apical positions and three F atoms belonging to different tetra­fluorido­borate anions in the equatorial plane. The material consists of infinite chains of [Ag(C14H12N2O4)] units running along [001], held together by BF4 − bridging anions. Javier Vallejos; Iván Brito; Alejandro Cárdenas; Michael Bolte article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/25270 Fri, 22 Jun 2012 17:21:16 +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/21907 The title compound (also know as azorellanone), C20H32O2, is built up from three fused carbocycles, one five-membered ring and two six-membered rings. The five membered-ring has an envelope conformation, whereas the six-membered rings have a distorted half-chair and a twist–boat conformation. In the crystal, mol­ecules are linked by O—H ... O inter­actions into zigzag chains with graph-set notation C(8) along [010]. The absolute configuration was assigned on the basis of earlier chemical studies. Iván Brito; Jorge Bórquez; Luis Alberto Loyola; Michael Bolte; Joselyn Albanez article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21907 Mon, 20 Jun 2011 10:13:24 +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/21889 In the title compound, C11H11N3O2, the dihedral angle between the central ethanone fragment and the 4-meth­oxy­phenyl group is 2.9 (2)°, while that between the ethanone fragment and the triazole ring is 83.4 (2)°. The dihedral angle between the planes of the triazole and benzene rings is 81.7 (1)°. The 4-meth­oxy­phenyl group is cis with respect to the ethanone fragment O atom across the exocyclic C—C bond. In the crystal, mol­ecules are linked by C—H ... N inter­actions into C(9) chains along [001]. Victor Kesternich; Iván Brito; Michael Bolte; Marcia Pérez-Fermann; Ronald Nelson article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21889 Fri, 17 Jun 2011 16:53:33 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21887 Iván Brito; Joselyn Albanez; Michael Bolte article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21887 Fri, 17 Jun 2011 16:24:43 +0200 http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21886 The title compound, [systematic name: 5a-acetoxymethyl-3-isopropyl-8-methyl-1,2,3,3a,4,5,5a,6,7,10,10a,10b-dodecahydro-7,10-endo-epidioxycyclohepta[e]indene-3a-carboxylic acid], C22H32O6 (I), is closely related to methyl 5a-acetoxymethyl-3-isopropyl-8-methyl-1,2,3,3a,4,5,5a,6,7,10,10a,10b-dodecahydro-7,10-endo-epidioxycyclohepta[e]indene-3a-carboxylate, (II) [Brito et al., (2008 [triangle]). Acta Cryst. E64, o1209]. There are two molecules in the asymmetric unit, which are linked by two strong intramolecular O—H ... O hydrogen bonds with graph-set motif R 2 2(8). In both (I) and (II), the conformation of the three fused rings are almost identical. The five-membered ring has an envelope conformation, the six-membered ring has a chair conformation and the seven-membered ring has a boat conformation. The most obvious differences between the two compounds is the observed disorder of the acetoxymethyl fragments in both molecules of the asymmetric unit of (I). This disorder is not observed in (II). The crystal structure and the molecular conformation is stabilized by intermolecular C—H ... O hydrogen bonds. The ability to form hydrogen bonds is different in the two compounds. The crystal studied was a non-merohedral twin, the ratio of the twin components being 0.28 (1):0.72 (1) Iván Brito; Jorge Bórquez; Joselyn Albanez; Michael Bolte; Luis Manuel Peña-Rodríguez article http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/21886 Fri, 17 Jun 2011 16:20:03 +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