McConnell equation

McConnell equation describes the proportional dependence of the hyperfine splitting constant $a$ on the spin density $\rho$ (the probability of an unpaired electron being on a particular atom) in aromatic radical compounds such as benzene radical anion $C_6H_6^-$.

$a=Q \rho$

$Q$ is an empirical constant that can range from 2.0 to 2.5 mT.

History

The equation is named after Harden M. McConnell of Stanford University, who first presented it in 1956 in an article in the Journal of Chemical Physics.

References

Peter Atkins, Julio de Paula, Atkins' Physical Chemistry, 9th ed., Oxford University Press, Oxford, 14, 556