ChemInform Abstract: Synthesis, Reactions, and Properties of ONO Systems

Abstract

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Chiral ureas with two electronegative substituents at 1‐N: An unusual case of coexisting pyramidal and almost planar 1‐N atoms in the same crystal

“…10 Also in this salt, 4 elongation of the NÀ ÀN 1 bond to 1.47 Å was found when compared with 1.45 Å for NÀ ÀN bond length in hydrazine. 11 The NÀ ÀN 1 bond length is similar to NÀ ÀN bond length, which is observed in NF 2 À ÀNF 2 (1.49 Å 12 ) and (MeO) 2 NÀ ÀN(OMe) 2 (1.48 Å 13 ) where this elongation is caused by n F -r* NÀ ÀN and n O(Me) -r* NÀ ÀN anomeric interactions, 13 respectively. This NÀ ÀN 1 bond destabilization by the n O -r* NÀ ÀN1 interaction causes possibility of nucleophilic substitution of pyridinium group in N-methoxy-N-(pyridinium)-N-tertalkylamine salts 4 and N-alkoxy-N-(pyridinium)-N 0 ,N 0 -dimethylurea salt.…”

“…10 Also in this salt, 4 elongation of the NÀ ÀN 1 bond to 1.47 Å was found when compared with 1.45 Å for NÀ ÀN bond length in hydrazine. 11 The NÀ ÀN 1 bond length is similar to NÀ ÀN bond length, which is observed in NF 2 À ÀNF 2 (1.49 Å 12 ) and (MeO) 2 NÀ ÀN(OMe) 2 (1.48 Å 13 ) where this elongation is caused by n F -r* NÀ ÀN and n O(Me) -r* NÀ ÀN anomeric interactions, 13 respectively.…”

“…[1][2][3][4] The pyramidality of nitrogen in the OÀ ÀNÀ ÀX geminal system (X 5 OC(O)R, OAlk, N 1 C 5 H 5 , Cl) in Nacyloxy-N-alkoxycarbamates, 5 N-acyloxy-N-alkoxyureas, 5,6 N,N-dialkoxyureas, 6 N-alkoxy-N-(1-pyridinium)urea salts, 6 and N-chloro-N-alkoxyureas 7 has been established by XRD study of their structure.…”

“…The solid was filtered off, the filtrate was evaporated to 50% in vacuo, the precipitate was filtered off, and the filtrate was further evaporated in vacuo. The residue was extracted by CH 2 X-ray diffraction study of compounds 1, 5, 7, and 8 was performed at Xcalibur 3 diffractometer (graphite-monochromated MoK a CCD detector, x-scans). Structures were solved by direct methods and refined by full-matrix least squares procedure in anisotropic approximation for nonhydrogen atoms using SHELX-97 program package.…”

“…The bonding of the nitrogen atom to two electronegative substituents possessing lone electron pairs (e.g., alkoxy groups in N,N-dialkoxy-N-tert-alkylamines 1 ) stabilizes pyramidality of the nitrogen atom and increases its inversion barrier. [1][2][3][4] The pyramidality of nitrogen in the OÀ ÀNÀ ÀX geminal system (X 5 OC(O)R, OAlk, N 1 C 5 H 5 , Cl) in Nacyloxy-N-alkoxycarbamates, 5 N-acyloxy-N-alkoxyureas, 5,6 N,N-dialkoxyureas, 6 N-alkoxy-N-(1-pyridinium)urea salts, 6 and N-chloro-N-alkoxyureas 7 has been established by XRD study of their structure.…”