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P21 Space Group (p21 + space_group)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Dicopper(II) Complexes with the Enantiomers of a Bidentate Chiral Reduced Schiff Base: Inclusion of Chlorinated Solvents and Chiral Recognition of1,2-Dichloroethane Rotamers in the Crystal Lattice

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2006
Vamsee Krishna Muppidi
Abstract Bisphenoxo-bridged dicopper(II) complexes [Cu2Ln2Cl2] {1 (n = 1) and 2 (n = 2)} with the N,O-donor reduced Schiff bases N -(2-hydroxybenzyl)-(R)-,-methylbenzylamine (HL1) and N -(2-hydroxybenzyl)-(S)-,-methylbenzylamine (HL2) have been synthesised and characterised. In both 1 and 2, the bidentate chiral ligands coordinate the metal centres through the secondary amine N atom and the bridging phenolate O atom. The chloride ion occupies the fourth coordination site and completes a slightly distorted square-planar NO2Cl environment around each copper(II) centre. Magnetic susceptibility measurements in the solid state suggest a strong antiferromagnetic interaction between the metal centres in both complexes. Both 1 and 2 readily form 1:1 host-guest compounds with chlorinated solvents such as CH2Cl2, CHCl3 and Cl(CH2)2Cl. All the host-guest compounds crystallise in noncentrosymmetric space groups. 1·CH2Cl2 and 2·CH2Cl2 crystallise in the P21 space group while 1·CHCl3, 2·CHCl3, 1·Cl(CH2)2Cl and 2·Cl(CH2)2Cl crystallise in the P212121 space group. In these inclusion crystals, the C,H···Cl interactions between the guest and the host molecules are primarily responsible for enclatheration of the chloroalkane molecules. In the case of CH2Cl2, one of its Cl atoms acts as the acceptor. On the other hand, for CHCl3 and Cl(CH2)2Cl, the metal coordinated Cl atom of the host complex acts as the acceptor. The structures of 1·(P)-Cl(CH2)2Cl and 2·(M)-Cl(CH2)2Cl provide rare examples for chiral recognition of the right handed (P) and the left handed (M) gauche forms of Cl(CH2)2Cl in molecular assemblies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Two polymorphs of N -(2,6-difluorophenyl)formamide

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009
Bernard Omondi
The structures of two distinct polymorphic forms of N -(2,6-difluorophenyl)formamide, C7H5F2NO, have been studied using single crystals obtained under different crystallizing conditions. The two forms crystallize in different space groups, viz. form (Ia) in the orthorhombic Pbca and form (Ib) in the monoclinic P21 space group. Each polymorph crystallizes with one complete molecule in the asymmetric unit and they have a similar molecular geometry, showing a trans conformation with the formamide group being out of the plane of the aromatic ring. The packing arrangements of the two polymorphs are quite different, with form (Ia) having molecules that are stacked in an alternating arrangement, linked into chains of N,H...O hydrogen bonds along the crystallographic a direction, while form (Ib) has its N,H...O hydrogen-bonded molecules stacked in a linear fashion. A theoretical study of the two structures allows information to be gained regarding other contributing interactions, such as ,,, and weak C,H...F, in their crystal structures. [source]

Emerging from pseudo-symmetry: the redetermination of human carbonic anhydrase II in monoclinic P21 with a doubled a axis

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2010
Arthur H. Robbins
The crystal structure of human carbonic anhydrase II in the monoclinic P21 space group with a doubled a axis from that of the usually observed unit cell has recently been reported, with one of the two molecules in the asymmetric unit demonstrating rotational disorder [Robbins et al. (2010), Acta Cryst. D66, 628,634]. The structure has been redetermined, with the coordinates of both pseudo-symmetrically related molecules in the crystallographic asymmetric unit translated by x, = x± 1/4, and no rotational disorder is observed. This corresponds to a different choice of how the four molecules in the unit cell should be grouped into pairs that represent a single asymmetric unit. [source]

Synthesis and Structure of Inclusion Complex of Cyclomaltoheptaose (,-Cyclodextrin) with m - Aminophenol

CHINESE JOURNAL OF CHEMISTRY, Issue 4 2002
Jin-Ling Wang
Abstract The supramolecular compound, ,-CD/m -aminophenol [(C42H70O35)·(C6H7ON)·(H2O)7.5·CH3OH], was synthesized and characterized by X-ray diffraction analysis. It crystallizes in monoclinic system, P21 space group, with a = 1.5122(4) nm, b=1.0335(4) nm, c=2.0915(3) nm, ,=109.58(2)°, V = 3.0798(3) nm3 and final R = 0.0598. The system belongs to "shallow inclusion" which is rarely found. In this supramolecule, the guest is located over the narrow rim of the host There are so many hydrogen bonds that they build a dense hydrogen bond net. The hydrogen-bond interactions are the main force to form the whole system and keep the stability. [source]