Ring current diamagnetic susceptibility

The key underlying assumption of all the NMR studies of the homotropenylium systems is that there is an induced ring current when the ions are in a magnetic field and that this effects the two C(8) protons in a different manner. Dauben, Wilson and Laity measured the diamagnetic susceptibility of 11 and showed that it has a susceptibility exaltation which is similar in magnitude to that of the tropylium ion88. 

Aromatic ring currents[45, 46] or the charge stiffness[47] provide a related application of correction vectors, now associated with magnetic fields. Ring currents are the diamagnetic susceptibility of 4n+2 systems. The correction vector in monocycles is obtained from... 

Magnetic property measurements led to a quantitative approach to aromaticity. Diamagnetic susceptibility was the first magnetic property studied in connection with the concept of resonance energy. More recently, H NMR spectroscopy has become a tool in the study of ring currents in cyclic 7t-conjugated systems. 

Aromatic compounds display magnetic properties related to a ring current. These include unusual chemical shifts, especially of protons, large magnetic anisotropies, and large diamagnetic susceptibility exaltations. 

---