Synthesis, reactivity, and X-ray crystal structures of [Os6Pt2H2(CO)16(µ-C8H10)(C8H12)]·CH2Cl2 and [Os6H(CO)16(µ-C8H11)]. Model compounds for C–H activation

Abstract

The reaction of [Os₆(CO)₁₆(NCMe)₂] with [Pt(C₈H₁₂)₂](C₈H₁₂= cyclo-octa-1,5-diene) results in the formation of [Os₆Pt₂H₂(CO)₁₆(µ-C₈H₁₀)(C₈H₁₂)](1). The geometry of (1) may be derived from that of [Os₆(CO)₁₈] by bridging one edge of the central Os tetrahedron with one Pt atom of the dimer unit Pt₂(µ-C₈H₁₀)(C₈H₁₂). One C₈H₁₂ group has been dehydrogenated to C₈H₁₀ and the two resulting hydride ligands are terminally bound to different metals of the Os₆ core. The C₈H₁₀ ligand is bound in an η³-ally1 fashion to one Pt atom and by an η²-olefinic bond and σ-alkyl bond to the second Pt atom. Upon heating in toluene, complex (1) rearranges to the known complex [Os₆Pt₂(CO)₁₆(C₈H₁₂)₂](3). Complex (3) is without hydride ligands and possesses a geometry of two edge-fused Os tetrahedra, one of which is Pt-bicapped. The complex [Os₆H(CO)₁₆(µ-C₈H₁₁)](2) was isolated from the reaction of [Os₆H(CO)₁₆(NCMe)₂] with C₈H₁₂. Complex (2) has the bicapped tetrahedral geometry of [Os₆(CO)₁₈] with the µ-C₈H₁₁ group bridging two Os atoms of the central tetrahedron. The hydride ligand caps a triangulated Os face. This complex reacts with CO to afford the parent cluster [Os₆(CO)₁₈].