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

Abstract

The reactivity of the dinuclear platinum(III) derivative [(R(F))2Pt(III)(μ-PPh2)2Pt(III)(R(F))2](Pt-Pt) (R(F) = 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[(R(F))2Pt(II)(μ-OPPh2)(μ-PPh2)Pt(II)(R(F))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[(R(F))2Pt(II)(μ-N3)(μ-PPh2)Pt(II)(R(F))2] (4a) and (b) formation of the P-C bond and reductive coupling with one of the C6F5 groups yielding [NBu4][(R(F))2Pt(II)(μ-N3)(μ-PPh2)Pt(II)(R(F))(PPh2R(F))] (4b). Analogous behavior was shown in the addition of NCO(-) to 1 which afforded [NBu4]2[(R(F))2Pt(II)(μ-NCO)(μ-PPh2)Pt(II)(R(F))2] (5a) and [NBu4][(R(F))2Pt(II)(μ-NCO)(μ-PPh2)Pt(II)(R(F))(PPh2R(F))] (5b). In the reaction of the trinuclear complex [(R(F))2Pt(III)(μ-PPh2)2Pt(III)(μ-PPh2)2Pt(II)(R(F))2](Pt(III)-Pt(III)) (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[(R(F))2Pt(II)(μ-Ph2PO)(μ-PPh2)Pt(II)(μ-PPh2)2Pt(II)(R(F))2] (6) and [NBu4][(R(F))2Pt(1)(μ3-Ph2PNPPh2)(μ-PPh2)Pt(2)(μ-PPh2)Pt(3)(R(F))2](Pt(2)-Pt(3)) (7). Complex 7 is fluxional in solution, and an equilibrium consisting of Pt-Pt bond migration was ascertained by (31)P EXSY experiments.