Ruthenium carbonyl cluster complexes with oxygen ligands. Part 2. Auration of a hexaruthenium ‘raft’ cluster; crystal structures of [Ru6(µ3-H)(µ-H)(µ-O:µ-C:η6-OC6H3OMe-4)(CO)16] and [AuRu6(µ3-H)(µ-O:µ-C:η6-OC6H3OMe-4)(CO)16(PPh3)]

Abstract

The hexaruthenium raft cluster [Ru₆(µ₃-H)(µ-H)(µ-O:µ-C:η⁶-OC₆H₃OMe-4)(CO)₁₆]1 is smoothly deprotonated by K-Selectride {K[B(CHMeEt)₃H] in tetrahydrofuran}, the resulting cluster anion being aurated by [AuCl(PPh₃)] to afford the mixed-metal cluster [AuRu₆(µ₃-H)(µ-O:µ-C:η⁶-OC₆H₃OMe-4)(CO)₁₆(PPh₃)]2 as the major product in moderate yield. The crystal structures of both 1 and 2 have been determined. The structural studies have revealed that isostructural replacement of H by isolobal Au(PPh₃) has not occurred; rather, an edge-bridging hydride has been replaced by a face-capping (phosphine)aurio moiety. In an analogous fashion to the auration, sequential reaction of 1 with K-Selectride and H₃PO₄ regenerated 1. By contrast, hydrogenation [1 atm (ca. 10⁵Pa) H₂, refluxing cyclohexane] of 1 resulted in expulsion of the ^–OC₆H₃OMe-4 ligand and formation of [Ru₄(µ-H)₄(CO)₁₂].