RESUMO
The crystal structures of three isomeric (E)-N'-(chloro-phenyl-methyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazides (C14H13ClN2OS) are described, with the Cl atom in ortho (I), meta (III) and para (IV) positions in the benzene ring. The ortho-bromo derivative (II) (C14H13BrN2OS), which is isostructural with its chloro congener (I), is also reported. Mol-ecules (I)-(III) have similar conformations, which approximate to l-shapes, as indicated by their N-C-C-Ct (t = thio-phene) torsion angles of -90.1â (3), -91.44â (18) and -90.7â (9)°, respectively. The conformation of (IV) is different, with an equivalent torsion angle of -170.75â (11)° corresponding to a more extended shape for the mol-ecule. The thio-phene ring in each structure features 'flip' rotational disorder. The packing for (I) and (II) features inversion dimers, linked by pairs of C-Hâ¯O inter-actions, which generate R22(14) loops. In the crystal of (III), [010] C(8) chains arise, with adjacent mol-ecules linked by pairs of C-Hâ¯O hydrogen bonds. The packing for (IV) features unusually short C-Hâ¯O inter-actions arising from an H atom attached to the benzene ring (Hâ¯O = 2.18â Å), which lead to C(9) [301] chains. Hirshfeld fingerprint percentage contact contributions are similar for the four title compounds.
RESUMO
The crystal structures of (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-benzyl-oxime, C12H12N4O3, (I), (E)-1-methyl-5-nitro-1H-imidazole-2-carb-alde-hyde O-(4-fluoro-benz-yl) oxime, C12H11FN4O3, (II), and (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-(4-bromo-benz-yl) oxime, C12H11BrN4O3, (III), are described. The dihedral angle between the ring systems in (I) is 49.66â (5)° and the linking Nm-C-C=N (m = methyl-ated) bond shows an anti conformation [torsion angle = 175.00â (15)°]. Compounds (II) and (III) are isostructural [dihedral angle between the aromatic rings = 8.31â (5)° in (II) and 5.34â (15)° in (III)] and differ from (I) in showing a near-syn conformation for the Nm-C-C=N linker [torsion angles for (II) and (III) = 17.64â (18) and 8.7â (5)°, respectively], which allows for the occurrence of a short intra-molecular C-Hâ¯N contact. In the crystal of (I), C-Hâ¯N hydrogen bonds link the mol-ecules into [010] chains, which are cross-linked by very weak C-Hâ¯O bonds into (100) sheets. Weak aromatic π-π stacking inter-actions occur between the sheets. The extended structures of (II) and (III) feature several C-Hâ¯N and C-Hâ¯O hydrogen bonds, which link the mol-ecules into three-dimensional networks, which are consolidated by aromatic π-π stacking inter-actions. Conformational energy calculations and Hirshfeld fingerprint analyses for (I), (II) and (III) are presented and discussed.
RESUMO
The crystal structures of 6-meth-oxy-1,3-benzoxa-thiol-2-one, C9H8O3S, (I), and 2-oxo-1,3-benzoxa-thiol-6-yl acetate, C9H6O4S, (II), are described. Compound (I) is almost planar (r.m.s. deviation for the non-H atoms = 0.011â Å), whereas (II) shows a substantial twist between the fused-ring system and the acetate substituent [dihedral angle = 74.42â (3)°]. For both structures, the bond distances in the heterocyclic ring suggest that little if any conjugation occurs. In the crystal of (I), C-Hâ¯O hydrogen bonds link the mol-ecules into [1-11] chains incorporating alternating R22(8) and R22(12) inversion dimers. The extended structure of (II) features C(7) [201] chains linked by C-Hâ¯O hydrogen bonds, with further C-Hâ¯O bonds and weak π-π stacking inter-actions connecting the chains into a three-dimensional network. Hirshfeld fingerprint analyses for (I) and (II) are presented and discussed.
RESUMO
The syntheses and crystal structures of (E)-N'-(3-cyano-benzyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazide, C15H13N3OS, (I), and (E)-N'-(4-meth-oxy-benzyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazide, C15H16N2O2S, (II), with different substituents in the meta and para position of the benzene ring are described. Compounds (I) and (II) both crystallize with two mol-ecules in the asymmetric unit, with generally similar conformations [r.m.s. overlay fits for (I) and (II) of 0.334 and 0.280â Å, respectively] that approximate to L-shapes. The thio-phene rings in (I) are well ordered, whereas those in (II) exhibit 'flip' rotational disorder [occupancies 0.662â (2) and 0.338â (2) for mol-ecule 1, and 0.549â (3) and 0.451â (3) for mol-ecule 2]. The packing for (I) features short C-Hâ¯O inter-actions arising from the C-H grouping adjacent to the cyanide group and C-Hâ¯Nc (c = cyanide) links arising from the methine groups to generate [110] double chains. Weak C-Hâ¯π inter-actions inter-link the chains into a three-dimensional network. The packing for (II) features numerous C-Hâ¯O and C-Hâ¯π inter-actions arising from different donor groups to generate a three-dimensional network. Hirshfeld fingerprint plots indicate significant differences in the percentage contact surfaces for (I) and (II).
RESUMO
The crystal structures of (3S,4aS,8aS)-2-[(2R,3S)-3-benzamido-2-benzo-yloxy-4-phenyl-but-yl]-N-tert-butyldeca-hydro-iso-quinoline-3-carboxamide, C38H47N3O4, (I), and (3S,4aS,8aS)-2-[(2R,3S)-3-(2,5-di-chloro-benzamido)-2-(2,5-di-chloro-benzo-yloxy)-4-phenyl-but-yl]-N-tert-butyldeca-hydro-iso-quinoline-3-carboxamide, C38H43Cl4N3O4, (II), are described. Despite their chemical similarity, they adopt different conformations in the solid state: (I) features a bifurcated intra-molecular N-Hâ¯(N,O) hydrogen bond from the tert-butylamide NH group to the piperidine N atom and the benzoate O atom, whereas (II) has an intra-molecular N-Hâ¯O link from the benzamide NH group to the tert-butyl-amide O atom. In the crystal of (I), mol-ecules are linked by C(4) amide N-Hâ¯O hydrogen bonds into chains propagating in the [010] direction, with both donor and acceptor parts of the benzamide group. In the extended structure of (II), C(11) N-Hâ¯O chains propagating in the [010] direction arise, with the donor being the tert-butylamide NH group and the acceptor being the O atom of the benzamide group.
RESUMO
The crystal structures of three isomeric (E)-N-methyl-N'-(nitro-benzyl-idene)-2-(thio-phen-2-yl)acetohydrazides (formula C14H13N3O3S) are described, with the nitro group in ortho, meta and para positions in the benzene ring. In each crystal structure, mol-ecules are linked by various weak inter-actions (C-Hâ¯O and C-Hâ¯π bonds, and π-π stacking), leading to three-dimensional networks in each case, but with little similarity between them.
RESUMO
The crystal structures of three methyl-ated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopro-pan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopro-pan-2-yl]carbamate, C16H23N3O4. One of them shows that an unexpected racemization has occurred during the mild-condition methyl-ation reaction. In each crystal structure, the mol-ecules are linked into chains by O-Hâ¯O hydrogen bonds, but with significant differences between them.
RESUMO
Oxazolidin-2-ones are widely used as protective groups for 1,2-amino alcohols and chiral derivatives are employed as chiral auxiliaries. The crystal structures of four differently substituted oxazolidinecarbohydrazides, namely N'-[(E)-benzylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12N3O3, (I), N'-[(E)-2-chlorobenzylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12ClN3O3, (II), (4S)-N'-[(E)-4-chlorobenzylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12ClN3O3, (III), and (4S)-N'-[(E)-2,6-dichlorobenzylidene]-N,3-dimethyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C13H13Cl2N3O3, (IV), show that an unexpected mild-condition racemization from the chiral starting materials has occurred in (I) and (II). In the extended structures, the centrosymmetric phases, which each crystallize with two molecules (A and B) in the asymmetric unit, form A+B dimers linked by pairs of N-H···O hydrogen bonds, albeit with different O-atom acceptors. One dimer is composed of one molecule with an S configuration for its stereogenic centre and the other with an R configuration, and possesses approximate local inversion symmetry. The other dimer consists of either R,R or S,S pairs and possesses approximate local twofold symmetry. In the chiral structure, N-H···O hydrogen bonds link the molecules into C(5) chains, with adjacent molecules related by a 21 screw axis. A wide variety of weak interactions, including C-H···O, C-H···Cl, C-H···π and π-π stacking interactions, occur in these structures, but there is little conformity between them.
Assuntos
Compostos de Benzilideno/química , Hidrazinas/química , Oxazóis/química , Cristalografia por Raios X , Ligação de Hidrogênio , Estrutura MolecularRESUMO
The title compounds, (C16H36N)2[Sn(C3OS4)3], (I), and (C24H20P)2[Sn(C3OS4)3], (II), are examples of complex salts of the general form [Q]2[Sn(dmio)3], where Q is nBu4N+ or Ph4P+ and dmio is the 2-oxo-1,3-dithiole-4,5-dithiolate dianion. Features of both structures are the slightly distorted octahedral coordination of tin in the propeller-shaped dianions and the absence of any significant inter-anion contacts. The structure of (I) is particularly notable because all of the dianions in the sample crystal have the same propeller configuration, which is very unusual in this type of structure.
RESUMO
The title compounds are salts of the general form (Q(+))(2)[Zn(dmit)(2)](2-), where dmit corresponds to the ligand (C(3)S(5))(-) present in both and Q(+) to the counter-cations ((n)Bu(4)N)(+) [or C(16)H(36)N(+)] and (Ph(4)As)(+) [or C(24)H(20)As(+)], respectively. In the first case, Zn is in the 4e special positions of space group C2/c and hence the [Zn(dmit)(2)](2-) dianion possesses twofold axial crystallographic symmetry. Including these, there are now 11 known examples of [Zn(dmit)(2)](2-) or its analogues, with O replacing the exocyclic thione S, and [Zn(dmio)(2)](2-) dianions in nine structures with various Q. Comparison of these reveals a remarkable variation in details of the conformation which the dianion may adopt in terms of Zn coordination, equivalence of the Zn-S bond lengths, displacement of Zn from the plane of the ligand and overall dianion shape.