Nickelatetrazoles as intermediates in the course of the photolysis of nickel(II) azido complexes? - A theoretical study

The primary photoreactions due to charge transfer excitation of d(8) transi tion metal complexes of [MP2(N-3)(2)] constitution (P-2: mono- or diphospha ne ligands) are strongly influenced by the central ion. While [MP2(N-3)(2)] complexes of both palladium(II) and platinum(II) yield primarily the corre sponding metal(I) species and azidyl radicals, nickel(II) complexes of the same constitution lead to intermediate generation of nitrenes as has been i ndirectly shown by various scavenging reactions. During the course of the s ucceeding reactions, the intermediate generation of nickelatetrazoles is as sumed. Both nitrene and metallatetrazole intermediates could not be identif ied directly so far. Therefore, the proposed reaction pathway has been mode led theoretically to get indications regarding the probability of the forma tion of such intermediates. Based on density functional theory (DFT) calcul ations, the energetics of the proposed pathway is compared with those of po ssible other pathways. The calculations support the proposed reaction pathw ay and point to possible reasons for the different behaviour of nickel(II) compared to palladium(Ir) and platinum(II).