The physico-chemical behaviour of tetraazadiene complexes.

The 1H nmr spectra at variable temperature for the series of tetraazadiene complexes M(NO) (PPh3)n (N4R2) (M = Rh, Ir; n = 1,2), Pt(L) (PPh3)(N4R2) (L = CO, PPh3;R = p-CH3C6H4SO2) have been studied. From the simulated 1H nmr spectra of the iridium complex (n = 1) the activation parameters for an isomerization process which takes place in solution have been calculated. Studies on the chemical reactivity of the tetraazadiene ligand bound to a transition metal have shown that the organic moiety is susceptible to attack only by mineral acids.