Nuclear magnetic resonance shift reagents: evidence for different mechanisms of contact contributions to C shifts induced by nickel and cobalt acetylacetonates with saturated amines and alcohols.
The pattern of (13)C and (1)H nuclear magnetic resonance (NMR) shift changes produced by complexation of cobalt and nickel acetylacetonates with amines and alcohols indicates that there is more than one mode of operation of the contact interaction. A large effect with alternating signs is important at the alpha and beta carbons, but this effect seems to be overlaid by another influence that appears to fall off monotonically as one proceeds away from the site of complexation.
Gates and Crellin Laboratories of Chemistry, California Institute of Technology, Pasadena, Calif. 91109.
S R
SR
Johns
R A
RA
Smith
G E
GE
Hawkes
J D
JD
Roberts