| The chemistry of the reaction of Os3(CO) 10(NCCH3)2 with RAuPPh3 (R=CH 3, C6H5) have been investigated. It has been found Au-C bond can be easily oxidatively added to osmium carbonyl clusters. The Os3AuCH3 cluster provides a robust platform to studying multicenter C-H bond transformations and for C-C bond formation via methyl migration/CO insertion processes, while ortho C-H bond activation was achieved on unsaturated mercury-triosmium carbonyl cluster complexes. In Chapter 1, a series of "CH3"Os3AuPPh3 clusters, Os 3(CO)10(mu-O=CCH3)( mu-AuPPh3), 1 Os3(CO)9(mu3-CH)(mu-H)2(mu-AuPPh3), 2 and CH3Os3(CO)12AuPPh3, 4 have been synthesized and isolated. Each of them is characterized by FT-IR, NMR (1H and 31P), Mass-spectra and single crystal X-ray diffractometer. Interestingly, the subsequent methyl C-H bonds activation (methyl, methylene and methylidyne transformation) and methyl migration/CO insertion occurs simultaneously. In addition, carbon monoxide can induce shifts of the bridging hydride ligands back to methylidyne ligand making methyl ligand reversely. CO-assisted C-H bond activation and formation mechanisms is established via ADF-based Molecular Orbital analyses, intermediate energy profile calculation as well as time dependent 1HNMR experiment. In Chapter 2, the gold phosphine group in the complex Os 3(CO)10(mu-Ph)(mu-AuPPh3), 7 can be replaced by mercury halide groups by reactions with mercury halides. The replacement of the AuPPh3 with HgI forms a new compound [Os3(CO) 10(mu-Ph)(mu-HgI)]4, 8 which is the tetramer of Os 3(CO)10(mu-Ph)(mu-HgI)]. The reaction of 7 and HgCl 2 yielded the compound Os3(CO)10(mu-Ph)(mu-Hg)(mu-Cl) 3Os(CO)3, 9, in which a separate Os(CO) 3 group and an unsaturated phenyl bridged Os3 cluster are linked by a bridging HgCl3 group. When heated to reflux in 80 degrees C, compound 8 was converted into the compound [Os3(CO) 9(mu3-C6H4)(mu-H)(mu3-Hg)] 2Os(CO)4, 10, which includes a triply bridging C6H4 benzyne ligand and one bridging hydrido ligand. The Os3HgC6H5 cluster is a platform to watch the C-H bond activation during phenyl to benzyne transformation. |
