Synthesis and Characterization of New Triangulo Derivatives of PtIPtIPtII, Including the First Platinum Cluster Binding Both Ethylene and CO

The terminal hydride in the (PtPtPtII)-Pt-I-Pt-I triangulo cluster Pt-3(mu-PBu2t)(3)(H)(CO)(2) (1) may be removed by one-electron oxidants such-as [Cp2Fe]PF6. Under carbon monoxide the reaction affords the symmetrical, cationic derivative [Pt-3(mu-PBu2t)(3)(CO)(3)]PF6 (2). By operating with an-excess of the suitable ligand, we also prepared [Pt-3(mu-PBu2t)(3)(CO)(2)(NCCH3)]PF6 (3) and [Pt-3(mu-PBu2t)(3)(CO)(2)(CH2 =CH2)]PF6 (4). New neutral triangular precursors were obtained by substitution of the CO ligands contained in 1 with isocyanides. The hydrides Pt-3(mu-PBu2t)(3)-, (H)(CNR)(2) (5, R = CH2Ph; 6, R = C6H4-p-CH3; 7,R = Bu-t) were isolated by this route. Complex 7 reacts with chloroform to give Pt-3(mu-PBu2t)(3)(Cl)(CNBut)(2), (8), which, under an excess of CNBut, yields the cationic derivative [Pt-3(mu-PBu2t)(3)(CNBut)(3)]Cl (9). The new triangulo clusters were characterized by multinuclear NMR spectroscopy and, as far as 4 and 7 are concerned, by single-crystal X-ray diffraction