scholarly journals Crystal structures and conformational analyses of three pyranochromene derivatives

2015 ◽  
Vol 71 (8) ◽  
pp. 926-930 ◽  
Author(s):  
K. Swaminathan ◽  
K. Sethusankar ◽  
G. Siva Kumar ◽  
M. Bakthadoss
Keyword(s):  
Crystal Structures ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Side Chain ◽  
Compound I ◽  
The Mean ◽  
Compound Ii ◽  
Short Contacts ◽  
Coumarin Ring ◽  
Chromene Ring

The title compounds, C27H20O6, (I) [systematic name: methyl 7-oxo-14-phenyl-1H,7H,14H-pyrano[3,2-c:5,4-c′]dichromene-14a(6bH)-carboxylate], C24H22O5, (II) [systematic name: methyl 1-oxo-6-phenyl-2,3,4,12b-tetrahydro-1H,6H-chromeno[3,4-c]chromene-6a(7H)-carboxylate], and C25H23N3O4, (III) [systematic name: 6-(4-ethylphenyl)-2,4-dimethyl-1,3-dioxo-2,3,4,12b-tetrahydro-1H,6H-chromeno[4′,3′:4,5]pyrano[2,3-d]pyrimidine-6a(7H)-carbonitrile], are pyranochromene derivatives. The central pyran rings (B) of compounds (I) and (III) adopt half-chair conformations, whereas that of compound (II) adopts a sofa conformation. The pyran rings (A) of the chromene ring systems of compounds (II) and (III) adopt half-chair conformations, while that of compound (I) adopts a sofa conformation. The mean plane of the central pyran rings (B) make dihedral angles of 70.02 (6), 61.52 (6) and 69.12 (7)°, respectively, with the mean planes of the chromene moieties (C+A) of compounds (I), (II) and (III). The bicyclic coumarin ring system (C+A+B+E) in compound (I) is almost planar (r.m.s. deviation = 0.042 Å). The carbonitrile side chain in compound (III) is very nearly linear, with the C—C[triple-bond]N angle being 176.6 (2)°. The cyclohexene ring (E), fused with the central pyran ring (B) in compound (II) adopts a sofa conformation. In the molecular structures of compounds (II) and (III), there are C—H...O short contacts, which generateS(7) ring motifs. In the crystal structures of the title compounds, molecules are linked by C—H...O hydrogen bonds, which generate molecular sheets parallel to theabplane, withR43(28) loops in (I), inversion dimers withR22(10) loops in (II) and chains along [010] withR22(12) ring motifs in (III). In the crystal structures of (I) and (III), there are also C—H...π interactions present, leading to the formation of a three-dimensional framework in (II) and to sheets parallel to (101) in (III).

scholarly journals Isotypic crystal structures of 2,6-dibromo-N,N-bis(4-nitrophenyl)aniline and 2,6-dichloro-N,N-bis(4-nitrophenyl)aniline

2014 ◽  
Vol 70 (8) ◽  
pp. 65-67 ◽  
Author(s):  
Paul Kautny ◽  
Johannes Fröhlich ◽  
Berthold Stöger ◽  
Matthias Weil
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Van Der Waals ◽  
Three Dimensional ◽  
Compound I ◽  
Dimensional Network ◽  
Phenyl Rings ◽  
The Mean ◽  
Compound Ii ◽  
Van Der Waals Radii

In the molecules of the two isotypic title compounds, C18H11Br2N3O4(I) and C18H11Cl2N3O4(II), the triphenylamine N atoms show no sign of pyramidalization, with marginal displacements of the N atoms from the mean plane of the three connecting C atoms: 0.0058 (13) Å for the Br compound (I) and 0.0074 (9) Å for the Cl compound (II). In the crystals, molecules are linked through C—H...O hydrogen bonds between phenyl rings and nitro groups and byX...O (X= Br, Cl) interactions, that are shorter than the sum of the van der Waals radii, leading to a three-dimensional network.

Zolmitriptan oxalate and zolmitriptan camphorsulfonate: the first structural study of salt complexes of the antimigraine drug zolmitriptan

2013 ◽  
Vol 69 (10) ◽  
pp. 1186-1191
Author(s):  
Balasubramanian Sridhar ◽  
Krishnan Ravikumar ◽  
Venkatasubramanian Hariharakrishnan
Keyword(s):  
Structural Study ◽  
Three Dimensional ◽  
Helical Chain ◽  
Side Chain ◽  
Indole Ring ◽  
Asymmetric Unit ◽  
Compound I ◽  
Space Group ◽  
Compound Ii ◽  
Ring Motif

Zolmitriptan hydrogen oxalate [(S)-dimethyl(2-{5-[(2-oxo-1,3-oxazolidin-4-yl)methyl]-1H-indol-3-yl}ethyl)azanium hydrogen oxalate], C16H22N3O2+·C2HO4−, (I), and zolmitriptan camphorsulfonate [(S)-dimethyl(2-{5-[(2-oxo-1,3-oxazolidin-4-yl)methyl]-1H-indol-3-yl}ethyl)azanium (S,R)-{2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methanesulfonate], C16H22N3O2+·C10H15O4S−, (II), are the first reported salt complexes of the antimigraine drug zolmitriptan. Compound (I) crystallizes in the space groupP21with two molecules of protonated zolmitriptan and two oxalate monoanions in the asymmetric unit, while compound (II) crystallizes in the space groupP212121with one protonated zolmitriptan molecule and one camphorsulfonate anion in the asymmetric unit. The orientations of the ethylamine side chain and the oxazolidinone ring with respect to the indole ring of the zolmitriptan cation are different for (I) and (II). In (I), they are oriented in opposite directions and the molecule adopts a step-like appearance, while in (II) the corresponding side chains are folded in the same direction, giving the molecule a cup-like appearance. The zolmitriptan molecules of (I) form anR22(8) dimer, while in (II) they form a helical chain with aC(11) motif. The oxalate monoanions of (I) interact with the zolmitriptan cations and extend the dimer into a three-dimensional hydrogen-bonded network. In (II), the camphorsulfonate anion forms anR22(15) ring motif with the zolmitriptan cation.

scholarly journals Crystal structures of three 6-aryl-2-(4-chlorobenzyl)-5-[(1H-indol-3-yl)methyl]imidazo[2,1-b][1,3,4]thiadiazoles

2020 ◽  
Vol 76 (1) ◽  
pp. 18-24
Author(s):  
Sadashivamurthy Shamanth ◽  
Kempegowda Mantelingu ◽  
Haruvegowda Kiran Kumar ◽  
Hemmige S. Yathirajan ◽  
Sabine Foro ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Three Dimensional ◽  
Asymmetric Unit ◽  
Compound I ◽  
Π Interactions ◽  
Reductive Condensation ◽  
Independent Molecules ◽  
Compound Ii

Three title compounds, namely, 2-(4-chlorobenzyl)-5-[(1H-indol-3-yl)methyl]-6-phenylimidazo[2,1-b][1,3,4]thiadiazole, C26H19ClN4S, (I), 2-(4-chlorobenzyl)-6-(4-fluorophenyl)-5-[(1H-indol-3-yl)methyl]imidazo[2,1-b][1,3,4]thiadiazole, C26H18ClFN4S, (II), and 6-(4-bromophenyl)-2-(4-chlorobenzyl)-5-[(1H-indol-3-yl)methyl]imidazo[2,1-b][1,3,4]thiadiazole, C26H18BrClN4S, (III), have been prepared using a reductive condensation of indole with the corresponding 6-aryl-2-(4-chlorobenzyl)imidazo[2,1-b][1,3,4]thiadiazole-5-carbaldehydes (aryl = phenyl, 4-fluorophenyl or 4-bromophenyl), and their crystal structures have been determined. The asymmetric unit of compound (I) consists of two independent molecules and one of the molecules exhibits disorder of the 4-chlorobenzyl substituent with occupancies 0.6289 (17) and 0.3711 (17). Each type of molecule forms a C(8) chain motif built from N—H...N hydrogen bonds, which for the fully ordered molecule is reinforced by C—H...π interactions. In compound (II), the chlorobenzyl unit is again disordered, with occupancies 0.822 (6) and 0.178 (6), and the molecules form C(8) chains similar to those in (I), reinforced by C—H...π interactions involving only the major disorder component. The chlorobenzyl unit in compound (III) is also disordered with occupancies of 0.839 (5) and 0.161 (5). The molecules are linked by a combination of one N—H...N hydrogen bond and four C—H...π interactions, forming a three-dimensional framework.

scholarly journals Crystal structures of two new carbazole derivatives: 12-(4-nitrophenyl)-7-phenylsulfonyl-7H-benzofuro[2,3-b]carbazole and 2-methyl-4-(4-nitrophenyl)-9-phenylsulfonyl-9H-thieno[2,3-b]carbazole

2016 ◽  
Vol 72 (12) ◽  
pp. 1739-1743
Author(s):  
K. Swaminathan ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Velu Saravanan ◽  
Arasambattu K. Mohanakrishnan
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Ring System ◽  
Molecular Structures ◽  
Dihedral Angles ◽  
Compound I ◽  
Carbazole Derivatives ◽  
Phenyl Rings ◽  
The Mean ◽  
Compound Ii

The title compounds, C30H18N2O5S, (I), and C27H18N2O4S2, (II), are carbazole derivatives with a phenylsulfonyl group and a nitrophenyl group attached to the carbazole moiety in identical positions in both molecules. A benzofuran ring system in (I) and a methylthiophene ring in (II) are fused with the respective carbazole moieties on the same sides. The mean plane of the carbazole ring system makes a dihedral angle of 3.17 (7)° with the benzofuran ring system in (I) and a dihedral angle of 3.39 (11)° with the methylthiophene ring in (II), implying that both fused units are essentially planar. The mean planes of the carbazole ring systems in both the compounds are almost orthogonal to the respective nitro-substituted phenyl rings, making dihedral angles of 75.64 (10) and 77.63 (12)° in compounds (I) and (II), respectively. In (I), the phenylsulfonyl ring system is positionally disordered with a refined occupancy ratio of 0.63 (2):0.37 (2). In both compounds, the molecular structures are stabilized by intramolecular C—H...O hydrogen bonds, generatingS(6) ring motifs with the sulfone group O atoms. In the crystal of compound (I), molecules are linked by pairs of C—H...O hydrogen bonds, which generateR22(18) inversion dimers, and interconnected byC(14) chains running along thec-axis direction, whereas in compound (II), the C—H...O hydrogen bonds generateR43(37) ring motifs. In the crystals of both compounds, C—H...O hydrogen-bonded sheets are formed lying parallel to (10-1). In addition, C—H...π and offset π–π interactions [intercentroid distance = 3.7158 (14) Å in (I) and 3.9040 (15) Å in (II)] are also present in the crystals of both compounds.

scholarly journals (E)-2-{[(2-Aminophenyl)imino]methyl}-5-(benzyloxy)phenol and (Z)-3-benzyloxy-6-{[(5-chloro-2-hydroxyphenyl)amino]methylidene}cyclohexa-2,4-dien-1-one

2018 ◽  
Vol 74 (5) ◽  
pp. 737-742
Author(s):  
Nadir Ghichi ◽  
Ali Benboudiaf ◽  
Chawki Bensouici ◽  
Yacine DJebli ◽  
Hocine Merazig
Keyword(s):  
Hydrogen Bond ◽  
Schiff Base ◽  
Density Functional ◽  
Tautomeric Form ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Compound I ◽  
Phenyl Rings ◽  
Imine Bond ◽  
Compound Ii

The title Schiff base compounds, C20H18N2O2(I) and C20H16ClNO3(II), were synthesized from 4-benzyloxy-2-hydroxybenzaldehyde by reaction with 1,2-diaminobenzene for (I), and condensation with 2-amino-4-chlorophenol for (II). Compound (I) adopts the enol–imine tautomeric form with anEconfiguration about the C=N imine bond. In contrast, theo-hydroxy Schiff base (II), is in the keto–imine tautomeric form with aZconfiguration about the CH—NH bond. Neither molecule is planar. In (I), the central benzene ring makes dihedral angles of 46.80 (10) and 78.19 (10)° with the outer phenylamine and phenyl rings, respectively, while for (II), the corresponding angles are 5.11 (9) and 58.42 (11)°, respectively. The molecular structures of both compounds are affected by the formation of intramolecular contacts, an O—H...N hydrogen bond for (I) and an N—H...O hydrogen bond for (II); each contact generates anS(6) ring motif. In the crystal of (I), strong N—H...O hydrogen bonds form zigzag chains of molecules along theb-axis direction. Molecules are further linked by C—H...π interactions and offset π–π contacts and these combine to form a three-dimensional network. The density functional theory (DFT) optimized structure of compound (II), at the B3LYP/6–311+G(d) level, confirmed that the keto tautomeric form of the compound, as found in the structure determination, is the lowest energy form. The antioxidant capacities of both compounds were determined by the cupric reducing antioxidant capacity (CUPRAC) process.

scholarly journals The crystal structures of three pyrazine-2,5-dicarboxamides: three-dimensional supramolecular structures

2017 ◽  
Vol 73 (5) ◽  
pp. 729-734
Author(s):  
Dilovan S. Cati ◽  
Helen Stoeckli-Evans
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Supramolecular Structure ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Inversion Symmetry ◽  
Compound I ◽  
Space Group ◽  
Π Interactions

The complete molecules of the title compounds,N2,N5-bis(pyridin-2-ylmethyl)pyrazine-2,5-dicarboxamide, C18H16N6O2(I), 3,6-dimethyl-N2,N5-bis(pyridin-2-ylmethyl)pyrazine-2,5-dicarboxamide, C20H20N6O2(II), andN2,N5-bis(pyridin-4-ylmethyl)pyrazine-2,5-dicarboxamide, C18H16N6O2(III), are generated by inversion symmetry, with the pyrazine rings being located about centres of inversion. Each molecule has an extended conformation with the pyridine rings inclined to the pyrazine ring by 89.17 (7)° in (I), 75.83 (8)° in (II) and by 82.71 (6)° in (III). In the crystal of (I), molecules are linked by N—H...N hydrogen bonds, forming layers lying parallel to thebcplane. The layers are linked by C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. In the crystal of (II), molecules are also linked by N—H...N hydrogen bonds, forming layers lying parallel to the (10-1) plane. As in (I), the layers are linked by C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. In the crystal of (III), molecules are again linked by N—H...N hydrogen bonds, but here form corrugated sheets lying parallel to thebcplane. Within the sheets, neighbouring pyridine rings are linked by offset π–π interactions [intercentroid distance = 3.739 (1) Å]. The sheets are linked by C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. Compound (I) crystallizes in the monoclinic space groupP21/c. Another monoclinic polymorph, space groupC2/c, has been reported on by Cockrielet al.[Inorg. Chem. Commun.(2008),11, 1–4]. The molecular structures of the two polymorphs are compared.

Synthesis and crystal structures of the potential tyrosinase inhibitorsN-(4-acetylphenyl)-2-chloroacetamide and 2-(4-acetylanilino)-2-oxoethyl cinnamate

2016 ◽  
Vol 72 (2) ◽  
pp. 94-98 ◽  
Author(s):  
Zaman Ashraf ◽  
Daeyoung Kim ◽  
Sung-Yum Seo ◽  
Sung Kwon Kang
Keyword(s):  
Crystal Structures ◽  
Dihedral Angle ◽  
Three Dimensional ◽  
Molecular Geometry ◽  
Compound I ◽  
Dimensional Network ◽  
Amide Carbonyl ◽  
Dermatological Disorders ◽  
Tyrosinase Enzyme ◽  
Compound Ii

Substituted benzoic acid and cinnamic acid esters are of interest as tyrosinase inhibitors and the development of such inhibitors may help in diminishing many dermatological disorders. The tyrosinase enzyme has also been linked to Parkinson's disease. In view of hydroxylated compounds having ester and amide functionalities to potentially inhibit tyrosinase, we herein report the synthesis and crystal structures of two amide-based derivatives, namelyN-(4-acetylphenyl)-2-chloroacetamide, C10H10ClNO2, (I), and 2-(4-acetylanilino)-2-oxoethyl cinnamate, C19H17NO4, (II). In compound (I), the acetylphenyl ring and the N—(C=O)—C unit of the acetamide group are almost coplanar, with a dihedral angle of 7.39 (18)°. Instead of esterification, a cheaper and more efficient synthetic method has been developed for the preparation of compound (II). The molecular geometry of compound (II) is a V-shape. The acetamide and cinnamate groups are almost planar, with mean deviations of 0.088 and 0.046 Å, respectively; the dihedral angle between these groups is 77.39 (7)°. The carbonyl O atoms are positionedsynandantito the amide carbonyl O atom. In the crystals of (I) and (II), N—H...O, C—H...O and C—H...π interactions link the molecules into a three-dimensional network.

scholarly journals Crystal structures of two mixed-valence copper cyanide complexes withN-methylethylenediamine

2017 ◽  
Vol 73 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Peter W. R. Corfield ◽  
Alexander Sabatino
Keyword(s):  
Crystal Structures ◽  
Close Contact ◽  
Mixed Valence ◽  
Three Dimensional ◽  
Molecular Compound ◽  
Compound I ◽  
Copper Cyanide ◽  
Dimensional Network ◽  
Covalently Linked ◽  
Compound Ii

The crystal structures of two mixed-valence copper cyanide compounds involvingN-methylethylenediamine (meen), are described. In compound (I), poly[bis(μ3-cyanido-κ3C:C:N)tris(μ2-cyanido-κ2C:N)bis(N-methylethane-1,2-diamine-κ2N,N′)tricopper(I)copper(II)], [Cu4(CN)5(C3H10N2)2] or Cu4(CN)5meen2, cyanide groups link CuIatoms into a three-dimensional network containing open channels parallel to thebaxis. In the network, two tetrahedrally bound CuIatoms are bonded by the C atoms of two end-on bridging CN groups to form Cu2(CN)6moieties with the Cu atoms in close contact at 2.560 (1) Å. Other trigonally bound CuIatoms link these units together to form the network. The CuIIatoms, coordinated by two meen units, are covalently linked to the networkviaa cyanide bridge, and project into the open network channels. In the molecular compound (II), [(N-methylethylenediamine-κ2N,N′)copper(II)]-μ2-cyanido-κ2C:N-[bis(cyanido-κC)copper(I)] monohydrate, [Cu2(CN)3(C3H10N2)2]·H2O or Cu2(CN)3meen2·H2O, a CN group connects a CuIIatom coordinated by two meen groups with a trigonal–planar CuIatom coordinated by CN groups. The molecules are linked into centrosymmetric dimersviahydrogen bonds to two water molecules. In both compounds, the bridging cyanide between the CuIIand CuIatoms has the N atom bonded to CuIIand the C atom bonded to CuI, and the CuIIatoms are in a square-pyramidal coordination.

scholarly journals Crystal structures of {[Cu(Lpn)2][Fe(CN)5(NO)]·H2O}nand {[Cu(Lpn)2]3[Cr(CN)6]2·5H2O}n[where Lpn = (R)-propane-1,2-diamine]: two heterometallic chiral cyanide-bridged coordination polymers

2015 ◽  
Vol 71 (4) ◽  
pp. 392-397
Author(s):  
Olha Sereda ◽  
Helen Stoeckli-Evans
Keyword(s):  
Hydrogen Bonds ◽  
Coordination Polymers ◽  
Three Dimensional ◽  
Water Molecules ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Compound I ◽  
Distorted Octahedral ◽  
Coordination Spheres ◽  
Compound Ii

The title compounds,catena-poly[[[bis[(R)-propane-1,2-diamine-κ2N,N′]copper(II)]-μ-cyanido-κ2N:C-[tris(cyanido-κC)(nitroso-κN)iron(III)]-μ-cyanido-κ2C:N] monohydrate], {[Cu(Lpn)2][Fe(CN)5(NO)]·H2O}n, (I), and poly[[hexa-μ-cyanido-κ12C:N-hexacyanido-κ6C-hexakis[(R)-propane-1,2-diamine-κ2N,N′]dichromium(III)tricopper(II)] pentahydrate], {[Cu(Lpn)2]3[Cr(CN)6]2·5H2O}n, (II) [where Lpn = (R)-propane-1,2-diamine, C3H10N2], are new chiral cyanide-bridged bimetallic coordination polymers. The asymmetric unit of compound (I) is composed of two independent cation–anion units of {[Cu(Lpn)2][Fe(CN)5)(NO)]} and two water molecules. The FeIIIatoms have distorted octahedral geometries, while the CuIIatoms can be considered to be pentacoordinate. In the crystal, however, the units align to form zigzag cyanide-bridged chains propagating along [101]. Hence, the CuIIatoms have distorted octahedral coordination spheres with extremely long semicoordination Cu—N(cyanido) bridging bonds. The chains are linked by O—H...N and N—H...N hydrogen bonds, forming two-dimensional networks parallel to (010), and the networks are linkedviaN—H...O and N—H...N hydrogen bonds, forming a three-dimensional framework. Compound (II) is a two-dimensional cyanide-bridged coordination polymer. The asymmetric unit is composed of two chiral {[Cu(Lpn)2][Cr(CN)6]}−anions bridged by a chiral [Cu(Lpn)2]2+cation and five water molecules of crystallization. Both the CrIIIatoms and the central CuIIatom have distorted octahedral geometries. The coordination spheres of the outer CuIIatoms of the asymmetric unit can be considered to be pentacoordinate. In the crystal, these units are bridged by long semicoordination Cu—N(cyanide) bridging bonds forming a two-dimensional network, hence these CuIIatoms now have distorted octahedral geometries. The networks, which lie parallel to (10-1), are linkedviaO—H...O, O—H...N, N—H...O and N—H...N hydrogen bonds involving all five non-coordinating water molecules, the cyanide N atoms and the NH2groups of the Lpn ligands, forming a three-dimensional framework.

Structural Studies on N-(2,4,6-Trimethylphenyl)-methyl/ chloro-acetamides, 2,4,6-(CH3)3C6H2NH-CO-CH3–yXy (X = CH3 or Cl and y = 0, 1, 2)

2006 ◽  
Vol 61 (10-11) ◽  
pp. 588-594 ◽  
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Jozef Kožíšek ◽  
Hartmut Fuess
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Data ◽  
The Other ◽  
Side Chain ◽  
Structural Studies ◽  
Asymmetric Unit ◽  
Lattice Constants ◽  
Peptide Linkage ◽  
The Mean

TMPAThe effect of substitutions in the ring and in the side chain on the crystal structure of N- (2,4,6-trimethylphenyl)-methyl/chloro-acetamides of the configuration 2,4,6-(CH3)3C6H2NH-COCH3− yXy (X = CH3 or Cl and y = 0,1, 2) has been studied by determining the crystal structures of N-(2,4,6-trimethylphenyl)-acetamide, 2,4,6-(CH3)3C6H2NH-CO-CH3 (); N-(2,4,6- trimethylphenyl)-2-methylacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH2-CH3 (TMPMA); N-(2,4,6- trimethylphenyl)-2,2-dimethylacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH(CH3)2 (TMPDMA) and N-(2,4,6-trimethylphenyl)-2,2-dichloroacetamide, 2,4,6-(CH3)3C6H2NH-CO-CHCl2 (TMPDCA). The crystallographic system, space group, formula units and lattice constants in Å are: TMPA: monoclinic, Pn, Z = 2, a = 8.142(3), b = 8.469(3), c = 8.223(3), β = 113.61(2)◦; TMPMA: monoclinic, P21/n, Z = 8, a = 9.103(1), b = 15.812(2), c = 16.4787(19), α = 89.974(10)◦, β = 96.951(10)◦, γ =89.967(10)◦; TMPDMA: monoclinic, P21/c, Z = 4, a =4.757(1), b= 24.644(4), c =10.785(2), β = 99.647(17)◦; TMPDCA: triclinic, P¯1, Z = 2, a = 4.652(1), b = 11.006(1), c = 12.369(1), α = 82.521(7)◦, β = 83.09(1)◦, γ = 79.84(1)◦. The results are analyzed along with the structural data of N-phenylacetamide, C6H5NH-CO-CH3; N-(2,4,6-trimethylphenyl)-2-chloroacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH2Cl; N-(2,4,6-trichlorophenyl)-acetamide, 2,4,6-Cl3C6H2NH-COCH3; N-(2,4,6-trichlorophenyl)-2-chloroacetamide, 2,4,6-Cl3C6H2NH-CO-CH2Cl; N-(2,4,6-trichlorophenyl)- 2,2-dichloroacetamide, 2,4,6-Cl3C6H2NH-CO-CHCl2 and N-(2,4,6-trichlorophenyl)- 2,2,2-trichloroacetamide, 2,4,6-Cl3C6H2NH-CO-CCl3. TMPA, TMPMA and TMPDCA have one molecule each in their asymmetric units, while TMPDMA has two molecules in its asymmetric unit. Changes in the mean ring distances are smaller on substitution as the effect has to be transmitted through the peptide linkage. The comparison of the other bond parameters reveal that there are significant changes in them on substitution.

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