Synthesis and Reactivity of the Unsaturated Trinuclear Phosphanido Complex [(C6F5)2Pt(μ-PPh2)2Pt(μ-PPh2)2Pt(PPh3)]

The reaction of [NBu4]­[(C6F5)2Pt­(μ-PPh2)2Pt­(μ-PPh2)2Pt­(O,O-acac)] (48 VEC) with [HPPh3]­[ClO4] gives the 46 VEC unsaturated [(C6F5)2Pt1(μ-PPh2)2Pt2(μ-PPh2)2Pt3(PPh3)]­(Pt2–Pt3) (1), a trinuclear compound endowed with a Pt–Pt bond. This compound displays amphiphilic behavior and reacts easily with nucleophiles L, yielding the saturated complexes [(C6F5)2PtII(μ-PPh2)2PtII(μ-PPh2)2PtII(PPh3)­L] [L = PPh3 (2), py (3)]. The reaction with the electrophile [Ag­(OClO3)­PPh3] affords the adduct 1·AgPPh3, which evolves, even at low temperature, to a mixture in which [(C6F5)2PtIII(μ-PPh2)2PtIII(μ-PPh2)2PtII(PPh3)2]2+(PtIII–PtIII) and 2 (plus silver metal) are present. The nucleophilic nature of 1 is also demonstrated through its reaction with cis-[Pt­(C6F5)2(THF)2], which results in the formation of [Pt4(μ-PPh2)4(C6F5)4(PPh3)] (4). The structure and NMR features indicate that 1 can be better considered as a PtII–PtIII–PtI complex instead of a PtII–PtII–PtII derivative. Theoretical calculations (density functional theory) on similar model compounds are in agreement with the assigned oxidation states of the metal centers. The strong intermetallic interactions resulting in a Pt2–Pt3 metal–metal bond and the respective bonding mechanism were verified by employing a multitude of computational techniques (natural bond order analysis, the Laplacian of the electron density, and localized orbital locator profiles).