Coupling Constants

Energy level of a nuclei are affected by covalently-bonded neighbors spin-states

1

3

C

1

H

1

H

1

H

one-bond

three-bond

aa

ab

ba

bb

I   S

S

S

I

I

J (Hz)

Spin-States of covalently-bonded nuclei want to be aligned.

The magnitude of the separation is called coupling constant (J) and has units of Hz.

+J/4

-J/4

+J/4