A trinuclear Pt(II) compound with short Pt-Pt-Pt contacts. An analysis of the influence of pi-pi stacking interactions on the strength and length of the Pt-Pt bond.

In this work we report the first example of a trinuclear Pt(II) complex with Pt-Pt-Pt bonds that are not facilitated by direct intervention of bridging ligands but are partially held by the attractive pi-pi stacking interaction between the phenyl units of the 4,4'-dimethyl-2,2'-bipyridyl ligands. The effect of the pi-pi stacking interactions on the strength and length of the Pt-Pt bond has been discussed using reduced models of the interacting moieties in which the aromatic rings have been removed. The nature of the Pt-Pt bonds has been studied through energy decomposition and atoms-in-molecules analyses. The results indicate that the relatively strong (about 40 kcal mol(-1)) Pt-Pt metallic bond has similar covalent and ionic contributions.