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

The reaction of [NBu4][(C6F5)(2)Pt(mu-PPh2)(2)Pt(mu-PPh2)(2)Pt(O,O-acac)] (48 VEC) with [HPPh3][ClO4] gives the 46 VEC unsaturated [(C6F5)(2)Pt-1(mu-PPh2)(2)Pt-2(mu-PPh2)(2)Pt-3(PPh3)](Pt-2-Pt-3) (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)(2)Pt-II(mu-PPh2)(2)Pt-II(mu-PPh2)(2)Pt-II(PPh3)L] [L = PPh3 (2), py (3)]. The reaction with the electrophile [Ag(OClO3)PPh3] affords the adduct 1 center dot AgPPh3, which evolves, even at low temperature, to a mixture in which [(C6F5)(2)Pt-III(mu-PPh2)(2)Pt-III(mu-PPh2)(2)Pt-II(PPh3)(2)](2+)(Pt-III-Pt-III) 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 [Pt-4(mu-PPh2)(4)(C6F5)(4)(PPh3)] (4). The structure indicate that 1 can be better considered as a Pt-II-Pt-III-Pt-I complex instead of a Pt-II-Pt-II-Pt-II 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 Pt-2-Pt-3 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).