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Application of the topological analysis of 13 C chemical shifts to the elucidation of the electronic and steric features of polyoxygenated benzenes with different substituents. Simulation of the 13 C NMR spectra
Author(s) -
Dostovalova Valentina I.,
Fedorov Lev A.
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260301209
Subject(s) - chemistry , chemical shift , steric effects , computational chemistry , oxygen , hydrogen bond , carbon fibers , nmr spectra database , carbon 13 nmr , ring (chemistry) , stereochemistry , molecule , topology (electrical circuits) , spectral line , organic chemistry , materials science , physics , mathematics , combinatorics , astronomy , composite number , composite material
A novel topological method was developed for the analysis of 13 C chemical shifts in polyoxygenated benzenes, C 6 H 6‐n (OY) n , where Y = H, Me and Ph. Carbon chemical shifts were described with individual and collective increments for oxygen itself and for oxygen substituents. The oxygens themselves have only one two‐particle increment (1,4‐dioxy interaction) in addition to the individual positional increments ( ipso , ortho , meta , para ). The 1,2‐dioxy interaction exerts no influence on any ring carbon chemical shifts, and thus the 1,2‐di‐ ortho ‐subgraphs were connected with the steric properties of the oxygen substituents. The results are in agreement with molecular mechanics calculations and NMR data in the solid state. Hydrogen bonding with specific solvents deshielded the ipso and ortho carbons by about 1.5 ppm. This predictive set completely described the 13 C NMR spectra of all the polyoxygenated benzenes studied within the experimental accuracy (RRMS = 0.6 ppm). The incremental scheme will be predictive and useful for PC programming.