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NMR analysis of a series of 1,2‐bis(1‐ R ‐5‐oxo‐2,3‐dihydro‐1 H ‐pyrrol‐4‐ylidene)ethanes and X‐ray crystal structure analysis of the R = mesityl compound
Author(s) -
Liu Qi,
Song XiuQing,
Yan Hong
Publication year - 2014
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229614020099
Subject(s) - chemistry , conjugated system , pyrrole , crystal structure , isopropyl , nuclear magnetic resonance spectroscopy , proton nmr , medicinal chemistry , crystal (programming language) , stereochemistry , crystallography , organic chemistry , polymer , computer science , programming language
Four tetramethyl 4,4′‐(ethane‐1,2‐diylidene)bis[1‐ R ‐5‐oxo‐4,5‐dihydro‐1 H ‐pyrrole‐2,3‐dicarboxylate] compounds, denoted class (1), are a series of conjugated buta‐1,3‐dienes substituted with a heterocyclic group. The compounds can be used as dyes and pigments due to their long‐range conjugated systems. Four structures were studied using 1 H NMR, 13 C NMR and mass spectroscopy, viz. with R = 2,4,6‐trimethylphenyl, (1 a ), R = cyclohexyl, (1 b ), R = tert ‐butyl, (1 c ), and R = isopropyl, (1 d ). A detailed discussion is presented regarding the characteristics of the three‐dimensional structures based on NMR analysis and the X‐ray crystal structure of (1 a ), namely tetramethyl 4,4′‐(ethane‐1,2‐diylidene)bis[5‐oxo‐1‐(2,4,6‐trimethylphenyl)‐4,5‐dihydro‐1 H ‐pyrrole‐2,3‐dicarboxylate], C 36 H 36 N 2 O 10 . The conjugation plane and stability were also studied via quantum chemical calculations.