Latest documents http://publikationen.ub.uni-frankfurt.de/index/index/ Fri, 14 Jun 2013 08:39:21 +0200 Fri, 14 Jun 2013 08:39:21 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/30055 The aromatic rings in the title compound, C13H8ClNO4, enclose a dihedral angle of 39.53 (3)°. The nitro group is almost coplanar with the ring to which it is attached [dihedral angle = 4.31 (1)°]. In the crystal, molecules are connected by C-H...O hydrogen bonds into chains running along [001]. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 A°; R factor = 0.044; wR factor = 0.105; data-to-parameter ratio = 18.9. Asma Iqbal; Toheed Akhter; Humaira Masood Siddiqi; Zareen Akhter; Michael Bolte article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/30055 Fri, 14 Jun 2013 08:39:21 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/25303 Mol­ecules of the title compound, C20H14O2, show approximate C s symmetry with the approximate mirror plane perpendicular to the central ring. The torsion angles about the acyclic bonds are 30.05 (15) and 30.77 (15)° in one half compared to −36.62 (14) and −18.60 (15)° in the other half of the mol­ecule. The central aromatic ring makes dihedral angles of 47.78 (4) and 51.68 (3)° with the two terminal rings. Ahmed Raza Ahsraf; Zareen Akhter; Michael Bolte article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/25303 Wed, 27 Jun 2012 12:42:31 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21917 The title compound, C14H11NO4, crystallizes with two mol­ecules in the asymmetric unit. The major conformational difference between these two mol­ecules is the dihedral angle between the aromatic rings, namely 36.99 (5) and 55.04 (5)°. The nitro groups are coplanar with the phenyl rings to which they are attached, the O—N—C—C torsion angles being -1.9 (3) and 1.0 (3)° in the two mol­ecules. Uzma Bibi; Humaira M. Siddiqi; Michael Bolte; Zareen Akhter article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21917 Mon, 20 Jun 2011 11:06:39 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21913 In the title compound, C17H11NO4, the dihedral angle between the two benzene rings is 8.66 (3)°. The nitro group is twisted by 4.51 (9)° out of the plane of the aromatic ring to which it is attached. The presence of inter­molecular C—H ... O contacts in the crystal structure leads to the formation of chains along the c axis. Uzma Bibi; Humaira M. Siddiqi; Zareen Akhter; Michael Bolte article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21913 Mon, 20 Jun 2011 10:36:47 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21903 The title compound, C22H28N2O6, crystallizes with four half-mol­ecules in the asymmetric unit: each mol­ecule is located about a crystallographic inversion centre. The central methyl­ene groups of two mol­ecules are disordered over two sets of equally occupied sites. The crystal packing is characterized by sheets of mol­ecules parallel to (114). Toheed Akhter; Humaira M. Siddiqia; Zareen Akhter; Michael Bolte article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21903 Mon, 20 Jun 2011 09:59:43 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21902 The dihedral angle between the two benzene rings in the title compound, C15H15NO2, is 65.28 (12)°. The crystal structure is stabilized by N—H ... N and N—H ... O hydrogen bonds, leading to the formation of supra­molecular chains along the a-axis direction. Ali Haider; Zareen Akhter; Muhammad Saif Ullah Khan; Michael Bolte; Humaira M. Siddiqia article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21902 Mon, 20 Jun 2011 09:56:27 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21901 In the title compound, C27H19N3O4, the phenol and pyrazole rings are almost coplanar [dihedral angle = 0.95 (12)°] due to an intra­molecular O—H ... N hydrogen bond, whereas the phenyl ring is tilted by 40.81 (7)° with respect to the plane of the pyrazole ring. The aromatic ring with a nitro­phen­oxy substituent makes a dihedral angle of 54.10 (7)° with the pyrazole ring. Ali Haider; Zareen Akhter; Michael Bolte; Muhammad Zia-ul Haq; Humaira M. Siddiqia article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/21901 Mon, 20 Jun 2011 09:52:57 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6968 The molecule of the title compound, C14H16N2O2, is located on a crystallographic twofold rotation axis. The central O-C-C-O bridge adopts a gauche conformation. One of the amine H atoms is disordered over two equally occupied positions. The crystal structure is stabilized by N-H...O and N-H...N hydrogen bonds. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 Å; disorder in main residue; R factor = 0.049; wR factor = 0.119; data-to-parameter ratio = 17.9. M. Saeed Butt; Zareen Akhter; Michael Bolte; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6968 Mon, 14 Sep 2009 08:37:12 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6966 In the title compound, C27H16F6N2O6, the nitro groups are almost coplanar with the aromatic rings to which they are attached [dihedral angles = 3.5 (5) and 6.2 (3)°]. The dihedral angles between adjacent aromatic rings are 78.07 (8) and 71.11 (8)° for nitrophenyl/phenyl and 69.50 (8)° for phenyl/phenyl. An intermolecular C-H...[pi] interaction seems to be effective in the stabilization of the structure. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.004 Å; R factor = 0.045; wR factor = 0.092; data-to-parameter ratio = 12.5. Haq Nawaz; Zareen Akhter; Michael Bolte; M. Saeed Butt; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6966 Fri, 11 Sep 2009 09:21:40 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6964 The title compound, C15H14N2O4, is an important intermediate for the synthesis of thermotropic liquid crystals. The dihedral angle between the two aromatic rings is 84.29 (4)°. An N-H...O hydrogen bond connects the molecules into chains running along the b axis. In addition, the crystal packing is stabilized by weak C-H...O hydrogen bonds. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 Å; R factor = 0.036; wR factor = 0.096; data-to-parameter ratio = 14.3. Asifa Nigar; Zareen Akhter; Michael Bolte; Humaira M. Siddiqi; Rizwan Hussain article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6964 Fri, 11 Sep 2009 09:10:08 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6959 In the title compound, C27H20F6N2O2, the dihedral angles between the planes of the aromatic rings connected by the ether O atoms are 84.13 (8) and 75.06 (9)°. The crystal structure is stabilized by N-H...O and N-H...F hydrogen bonds. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.004 Å; R factor = 0.037; wR factor = 0.088; data-to-parameter ratio = 8.2. Haq Nawaz; Zareen Akhter; Michael Bolte; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6959 Fri, 11 Sep 2009 08:29:33 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6954 The title compound, C12H17NO4, features an almost planar molecule (r.m.s. deviation for all non-H atoms = 0.070 Å). All methylene C-C bonds adopt an antiperiplanar conformation. In the crystal structure the molecules lie in planes parallel to (1\overline{1}2) and the packing is stabilized by O-H...O hydrogen bonds. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.003 Å; R factor = 0.066; wR factor = 0.185; data-to-parameter ratio = 13.2. Muhammad Saif Ullah Khan; Zareen Akhter; Michael Bolte; Sajjad A. Cheema; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6954 Thu, 10 Sep 2009 09:06:54 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6934 The title compound, C17H18N2O6, crystallizes with two molecules in the asymmetric unit. In both molecules, one of the C-C bonds of the pentamethylene chain connecting the two aromatic rings is in a trans conformation and another displays a gauche conformation. The aromatic rings within each molecule are nearly coplanar [dihedral angles = 3.36 (9) and 4.50 (9)°] and the nitro groups are twisted slightly out of the planes of their attached rings [dihedral angles = 8.16 (3)/6.6 (2) and 4.9 (4)/3.8 (3)°]. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.003 Å; R factor = 0.040; wR factor = 0.101; data-to-parameter ratio = 13.5. Muhammad Saif Ullah Khan; Zareen Akhter; Michael Bolte; M. Saeed Butt; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6934 Wed, 09 Sep 2009 08:43:35 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6922 In the title compound, C13H10N2O2, a Schiff base derivative, the dihedral angle between the two aromatic rings is 31.58 (3)°. The C=N double bond is essentially coplanar with the nitrophenyl ring. The torsion angle of the imine double bond is 175.97 (13)°, indicating that the C=N double bond is in a trans configuration. The crystal structure is stabilized by C-H...O contacts and [pi]-[pi] interactions (centroid-centroid distances of 3.807 and 3.808 Å). Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 Å; R factor = 0.034; wR factor = 0.093; data-to-parameter ratio = 10.3. Muhammad Zaheer; Zareen Akhter; Michael Bolte; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6922 Tue, 08 Sep 2009 09:21:38 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6900 The two phenyl rings of the biphenyl unit of the title compound, C18H13NO3, are almost coplanar [dihedral angle 6.70 (9)°]. The nitrophenyl ring, on the other hand, is significantly twisted out of the plane of the these two rings, making dihedral angles of 68.83 (4)° with the middle ring and 62.86 (4)° with the end ring. The nitro group is twisted by 12.1 (2)° out of the plane of the phenyl ring to which it is attached. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 A° ; R factor = 0.040; wR factor = 0.118; data-to-parameter ratio = 12.8. Zareen Akhter; Toheed Akhter; Michael Bolte; M. Amin Baig; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6900 Fri, 04 Sep 2009 14:28:13 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6870 The complete molecule of the title compound, C18H24N2O2, is generated by a crystallographic inversion centre. The torsion angles in the hexamethylene chain are consistent with an antiperiplanar conformation, whereas the conformation of the O-CH2-CH2-CH2 unit is gauche. The three-dimensional crystal packing is stabilized by N-H...O and N-H...N hydrogen bonding. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 A° ; R factor = 0.039; wR factor = 0.103; data-to-parameter ratio = 17.0. Muhammad Saif Ullah Khan; Zareen Akhter; Michael Bolte; Amna Siraj; Humaira M. Siddiqi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6870 Wed, 02 Sep 2009 13:07:24 +0200