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Two‐bond deuterium isotope effects on 13 C chemical shifts. A measure of carboncarbon bond lengths
Author(s) -
Sardella D. J.,
ElDin Alyaa Emad
Publication year - 1989
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.1260270312
Subject(s) - chemistry , deuterium , bond length , kinetic isotope effect , cyclohexene , double bond , carbon fibers , carbon–carbon bond , chemical shift , computational chemistry , organic chemistry , molecule , atomic physics , physics , materials science , composite number , composite material , catalysis
Two‐bond deuterium‐induced isotope effects ( 2 Δ) have been studied in several neutral π‐systems (6,6‐dimethylfulvene, cyclohexene and cyclohexa‐1,3‐diene). Isotope effects on the 13 C shifts of adjacent carbons are invariably to higher field, and vary from −84 to −139 ppb. In combination with literature data for a number of aromatic systems, these results establish that, for fragments of the type DC(sp 2 ) 13 C(sp 2 ) in five‐ or six‐membered rings, 2 Δ correlates linearly with carboncarbon bond length, the average deviation between calculated and experimental bond lengths being 0.01 Å. The correlation embraces bridgehead and non‐bridgehead carbons in both five‐ and six‐membered rings. As a test of the utility of this empirical relationship, 2 Δ in ferrocene‐d was determined to be −91 ppb, corresponding to a carboncarbon bond length of 1.42 Å, in good agreement with the experimental value of 1.43 Å.