RUTHENIUM CARBONYL CLUSTER COMPLEXES WITH OXYGEN LIGANDS .2. AURATION OF A HEXARUTHENIUM RAFT CLUSTER - CRYSTAL-STRUCTURES OF [RU6(MU-3-H)(MU-H)(MU-O, MU-C, ETA-6-OC6H3OME-4)(CO)16] AND [AURU6(MU-3-H)(MU-O, MU-C, ETA-6-OC6H3OME-4)(CO)16(PPH3)]

The hexaruthenium raft cluster [Ru6(mu3-H)(mu-H)(mu-O:mu-C:eta6-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(mu3-H)(mu-O:mu-C:mu6-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that isostructural replacement of H by isolobal Au(PPh3) has not occurred; rather, an edge-bridging hydride has been replaced by a face-capping (phosphine)aurio moiety.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. 10(5) Pa) H-2, refluxing cyclohexane] of 1 resulted in expulsion of the -OC6H3OMe-4 ligand and formation of [Ru4(mu-H)4(CO)12].