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Quantitative empirical treatment of 13 C NMR chemical shifts of aliphatic halides
Author(s) -
Suryanarayana Iragavarapu,
Gasteiger Johann
Publication year - 1991
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.1260291002
Subject(s) - chemistry , halogen , halide , alkyl , chemical shift , carbon 13 nmr , bicyclic molecule , atom (system on chip) , computational chemistry , medicinal chemistry , stereochemistry , organic chemistry , embedded system , computer science
The 13 C NMR chemical shifts of the α, β, γ and δ carbons of aliphatic fluorides, chlorides, bromides and iodides can be reproduced by a four‐parameter equation; the charge Q on the carbon atom, the number of hydrogen atoms three bonds away, N 3H , the interactions of the polarizabilities of the halogen atoms one bond away with the hydrogens present in the first sphere, as represented by P X N 1H , and the polarizabilities of halogens in the second sphere, P X (2). A regression coefficient of 0.9714 and a standard deviation of 4.85 ppm are obtained for all aliphatic halides in which the R skeleton includes alkyl, acyclic and bicyclic rings. For alkyl compounds only the correlation is of the order of R = 0.997 and the standard deviation is less than 2 ppm. Here the influence of C, H, F, Cl, Br and I are reproduced quantitatively.