Electron and nuclear spin relaxation in S = ½ paramagnetic transition-metal complexes

Abstract

Nuclear spin relaxation in some S = 1/2 paramagnetic transition-metal complexes is considered. If rotational reorientation dominates the electron and nuclear spin relaxation processes current theoretical treatments of spin relaxation provide an adequate description of the spin relaxation. However, there are many complexes where other time processes appear to be important. It is suggested that dynamic Jahn- Teller effects may be operative in Ru(acac)₃.     It is shown that the rotational Van Vleck mechanism is effectively the same relaxation mechanism as the so-called ?g-tensor? process. Although the Van Vleck mechanism is a useful reformulation of the same problem, it appears that this mechanism or any other rotationally induced electron spin relaxation process cannot adequately describe the nuclear relaxation times in a variety of para-magnetic transition-metal complexes.