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 [(R-F)(2)Pt-III(mu-PPh2)(2)Pt-III(R-F)(2)](Pt-Pt) (R-F=C6F5) (1) toward OH-, N-3(-), 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-, N-3(-), 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)(2)Pt-II(mu-OPPh2)(mu-PPh2)Pt-II(R-F)(2)] (3). The addition of N-3(-) takes place through two ways: (a) formation of the P-N bond and reductive elimination of PPh2N3 yielding [NBu4](2)[(R-F)(2)Pt-II(mu-N-3)(mu-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)(2)Pt-II(mu-N-3)(mu-PPh2)Pt-II(R-F)(PPh2RF)] (4b). Analogous behavior was shown in the addition of NCO- to 1 which afforded [NBu4](2)[(R-F)(2)Pt-II(mu-NCO)(mu-PPh2)Pt-II(R-F)(2)] (5a) and [NBu4][(R-F)(2)Pt-II(mu-NCO)(mu-PPh2)Pt-II(R-F)(PPh2RF)] (5b). In the reaction of the trinuclear complex [(R-F)(2)Pt-III(mu-PPh2)(2)Pt-III(mu-PPh2)(2)Pt-II(R-F)(2)] (Pt-III-Pt-III) (2) with OH- or N-3(-), the coordination of the nucleophile takes place selectively at the central platinum(III) center, and the PPh2/OH- or PPh2/N-3(-) reductive coupling yields the trinuclear [NBu4](2)[(R-F)(2)Pt-II(mu-Ph2PO)(mu-PPh2)Pt-II(mu-PPh2)(2)Pt-II(R-F)(2)] (6) and [NBu4][(R-F)(2)Pt-1(mu(3)-Ph2PNPPh2)(mu-PPh2)Pt-2(mu-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 P-31 EXSY experiments.