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NMR chemical shifts as probes for steric effects in mono‐ and disubstituted adamantanes
Author(s) -
Seidl Peter Rudolf,
Leal Kátia Zaccur,
Yoneda Julliane Diniz
Publication year - 2002
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.538
Subject(s) - chemistry , chemical shift , substituent , steric effects , ring strain , adamantane , computational chemistry , acetamide , carbon 13 nmr , ring (chemistry) , stereochemistry , organic chemistry
Substituent effects are widely used to investigate the factors affecting carbon‐13 chemical shifts. Adamantane and its derivatives are convenient probes for relative contributions to these factors owing to their symmetry and relative absence of ring strain. We have extended our studies on NMR chemical shifts of 1‐ and 2‐methyladamantanes to hydroxy, bromo, methoxy and acetamide substituents and also certain disubstituted (one of the groups being methyl) analogs. DFT/GIAO calculations at the B3LYP/6–31G(d,p) level show that, except for α‐effects, steric interactions are mainly responsible for substituent effects on chemical shifts. The CHARGE program is particularly well suited for localizing these effects and estimating their approximate shape and range.