Chemistry:McConnell equation

In physical chemistry, the McConnell equation gives the probability of an unpaired electron in an in aromatic radical compound (such as benzene radical anion [math]\displaystyle{ C_6H_6^- }[/math]) being on a particular atom. It relates this probability, known as the "spin density", to its proportional dependence on the hyperfine splitting constant. The equation is [math]\displaystyle{ a = Q \rho, }[/math] where [math]\displaystyle{ a }[/math] is the hyperfine splitting constant, [math]\displaystyle{ \rho }[/math] is the spin density, and [math]\displaystyle{ Q }[/math] 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.

References

• Atkins' Physical Chemistry (9th ed.). Oxford University Press.