Most of the kinetic data on inorganic systems in the literature relate to
compounds of Pt(l1) and Co(1II) (1,2). This is because the reactions involved
are slow enough to be studied by following concentration changes as a
function of time.
A fundamentally different approach which has been used increasingly
of late is the line-broadening technique in nuclear magnetic resonance spectroscopy.
The time scale here lies in the range of to lo-' sec. The essential
difference between the classical method (1,2) and the NMR method is that the
classical is applied to systems with changing concentrations of the reacting
species, whereas the NMR is employed for systems in a rapid equilibrium
where the lifetimes of species in equilibrium are measured. Reactions of
organic compounds have been studied extensively in this way, one of the early
examples of proton exchange being the hindered rotation of the methyl
amino groups in N,N-dimethylformamide (3,4). The technique has now been
applied successfully to reactions of organometallic compounds, particularly
to systems showing proton exchanges, since proton resonance has been most
readily accessible up to now