Addition of Nucleophiles to Phosphanido Derivatives of Pt(III): Formation of P–C, P–N, and P–O Bonds

The reactivity of the dinuclear platinum­(III) derivative [(RF)2PtIII(μ-PPh2)2­PtIII(RF)2](Pt–Pt) (RF = C6F5) (1) toward OH–, N3–, and NCO– was studied. The coordination of these nucleophiles to a metal center evolves with reductive coupling or reductive elimination between a bridging diphenylphosphanido group and OH–, N3–, and NCO– or C6F5 groups and formation of P–O, P–N, or P–C bonds. The addition of OH– to 1 evolves with a reductive coupling with the incoming ligand, formation of a P–O bond, and the synthesis of [NBu4]2[(RF)2PtII(μ-OPPh2)­(μ-PPh2)­PtII(RF)2] (3). The addition of N3– takes place through two ways: (a) formation of the P–N bond and reductive elimination of PPh2N3 yielding [NBu4]2[(RF)2PtII(μ-N3)­(μ-PPh2)­PtII(RF)2] (4a) and (b) formation of the P–C bond and reductive coupling with one of the C6F5 groups yielding [NBu4]­[(RF)2PtII(μ-N3)­(μ-PPh2)­PtII(RF)­(PPh2RF)] (4b). Analogous behavior was shown in the addition of NCO– to 1 which afforded [NBu4]2[(RF)2PtII(μ-NCO)­(μ-PPh2)­PtII(RF)2] (5a) and [NBu4]­[(RF)2PtII(μ-NCO)­(μ-PPh2)­PtII(RF)­(PPh2RF)] (5b). In the reaction of the trinuclear complex [(RF)2PtIII(μ-PPh2)2PtIII(μ-PPh2)2­PtII(RF)2](PtIII–PtIII) (2) with OH– or N3–, the coordination of the nucleophile takes place selectively at the central platinum­(III) center, and the PPh2/OH– or PPh2/N3– reductive coupling yields the trinuclear [NBu4]2[(RF)2PtII(μ-Ph2PO)­(μ-PPh2)­PtII(μ-PPh2)2PtII(RF)2] (6) and [NBu4]­[(RF)2Pt1(μ3-Ph2PNPPh2)­(μ-PPh2)­Pt2(μ-PPh2)­Pt3(RF)2](Pt2–Pt3) (7). Complex 7 is fluxional in solution, and an equilibrium consisting of Pt–Pt bond migration was ascertained by 31P EXSY experiments.