Synthesis, Dynamic Behavior, and Reactivity of New Unsaturated Heterotrinuclear 46 Valence Electron Complexes†Polynuclear Homo- or Heterometallic Palladium(II)−Platinum(II) Pentafluorophenyl Complexes Containing Bridging Diphenylphosphido Ligands. 27. For part 26, see ref .

The reaction of [NBu₄]₂[(C₆F₅)₂Pt(μ-PPh₂)₂Pd(μ-PPh₂)₂Pt(C₆F₅)₂] (1a) with [AgPPh₃]⁺ results in the oxidation of two bridging diphenylphosphanides to give the 46e species [(PPh₃)(C₆F₅)₂Pt²(μ-P²Ph₂)Pd(μ-PPh₂)(μ-Ph₂P⁴−P³Ph₂)Pt¹(C₆F₅)₂] (3). Complex 3 displays two tetracoordinated terminal platinum centers and a central Pd atom that is bonded to three P atoms and that completes its coordination sphere by a rather long (3.237 Å) dative Pt² → Pd bond. Complex 3 is also obtained when [(R_F)₂Pt(μ-PPh₂)Pd(μ-PPh₂)(μ-Ph₂P-PPh₂)Pt(R_F)₂] (2) is reacted with PPh₃. Analogously, the addition of PPh₂Et, CO or pyridine to 2 affords the 46e complexes of general formula [(L)(C₆F₅)₂Pt²(μ-P²Ph₂)Pd(μ-PPh₂)(μ-Ph₂P⁴−P³Ph₂)Pt¹(C₆F₅)₂] (L = PPh₂Et, 4; L = CO, 6; L = pyridine, 7). The geometry around Pt² is determined by the bulkiness of L bonded to Pt. Thus, in complexes 3 (L = PPh₃) and 4 (L = PPh₂Et), the ligand L occupies the trans position with respect to μ-P², and in 6 (L = CO), the ligand L occupies the cis position with respect to μ-P². Interestingly, for 7 (L = py), both isomers 7-trans and 7-cis, could be isolated. Although 4 did not react with an excess of PPh₂Et, the reaction with the less sterically demanding CH₃CN ligand resulted in the opening of the Pt²−P²−Pd cycle with formation of the saturated 48e species [(PPh₂Et)(C₆F₅)₂Pt(μ-PPh₂)Pd(MeCN)(μ-PPh₂)(μ-Ph₂P-PPh₂)Pt(C₆F₅)₂] (8). The saturated 48e complex [(CO)(C₆F₅)₂Pt(μ-PPh₂)Pd(MeCN)(μ-PPh₂)(μ-Ph₂P-PPh₂)Pt(C₆F₅)₂] (9) was obtained by acetonitrile addition to 6. Beside the hindered rotation of the pentafluorophenyl groups and a flip-flop motion of the Pd−P−Pt¹−P−P ring observed at low T, a rotation about the Pt²−P² bond and a P−C oxidative addition/reductive elimination process occur for 3 and 4 at room temperature. A “through-space” ¹⁹F−³¹P spin−spin coupling between an ortho-F and the P⁴ is observed for complexes 3 and 4, having the C₆F₅ groups bonded to Pt² in mutually trans position. The XRD structures of complexes 3, 6, 7-trans, 7-cis, 8, and 9 are described.