Aryl–perfluoroaryl stacking interactions, hydrogen bonding and steric effects in controlling the structure of supramolecular assemblies of N,N′-diaryloxalamides

Supramolecular architectures of conformationally controlled 1,3-phenyl-dioxalamic molecular clefts through hydrogen bonding and steric restraints

“…A common feature of conformers 1 and 1 0 is the twist of both oxalamate side arms, one of them tilted up and the other tilted down with regard to the mean plane of the phenyl ring. The outof-plane conformation is characteristic of disubstituted ethyl o-and p-phenyl-bis-oxalamates, 13 in contrast with the reported planar conformation of monosubstituted ethyl N-phenyl oxalamate. 14…”

“…White solid, mp: 194-196 C, IR n (neat) (cm À1 ): 3225 (N-H), 1685 (C] O). 1 H NMR: 8.47 (s, 2H, NH), 7.00 (s, 1H, Ph), 4.39 (q, 4H, O-CH 2 , 3 J ¼ 7.1), 2.17 (s, 6H, 2CH 3 ), 2.06 (s, 3H, CH 3 ), 1.41 (t, 6H, CH 2 -CH 3 , 3 J ¼ 7.1) 13. C NMR: 160.9 (C9), 155.1 (C8), 135.3 (C1, C3), 132.7 (C4, C6), 130.8 (C5), 130.4 (C2), 63.9 (C11),18.5 (2Me), 14.3 (Me), 14.1 (C12).…”

Dinuclear Tin(II) Complex of a Bulky cis‐Oxamide: Synthesis, Characterization, Crystal Structure, and DFT Studies

“…The low symmetry is due to a non‐planar array of the aromatic rings (torsion angle C1–N2–C3–C8 = 66.7°). The C1–O1 [1.208(4) Å], C1–N2 [1.327(4) Å], and C1–C11 [1.509(4) Å] bond lengths are slightly shorter than those of similar already reported oxamides (Me 3 C 6 H 2 NHCO) 2 , [C–O 1.2188(4) Å, C–N 1.337(5) Å, C–C 1.5338(3) Å] 18. Reaction of the di‐lithiated oxamides of 1 and 2 with two equivalents of SnCl 2 in THF at low temperature provided, after work‐up, compounds trans ‐ 3 and trans ‐ 4 , respectively, as amorphous materials in approximately 52 % yield (Scheme ).…”

Crystal structure oftrans-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)oxamide methanol monosolvate

“…Finally, in Ti, Zr and Hf complexes (Gü izado-Rodríguez et al, 2007), the metal displays a planar structure similar to that observed in Sn complexes, but no X-ray structures were determined. On the other hand, several phenol-oxamides have shown different conformations, ranging from completely flat (Weiss et al, 2015) to arrangements where the oxamide group presents a tilt angle, or is even almost completely perpendicular to the plane of the aromatic rings (Wen et al, 2006;Piotrkowska et al, 2007). Piotrkowska's group made a good analysis of the phenyl-oxamides and explained how the substituent groups on the aromatic rings and the presence of solvent influence the conformation of the oxamide group: hydrogen bonds andstacking between aromatic rings are the main forces responsible for the assembly of molecules within the crystal lattice.…”

“…Piotrkowska's group made a good analysis of the phenyl-oxamides and explained how the substituent groups on the aromatic rings and the presence of solvent influence the conformation of the oxamide group: hydrogen bonds andstacking between aromatic rings are the main forces responsible for the assembly of molecules within the crystal lattice. Thus, the steric effects of the bulky o-substituents cause twisting of the aryl ring from the oxamide plane, and interfere with the formation of hydrogen bonds (Piotrkowska et al, 2007).…”