Synthesis of [{Os 3(CO) 10(μ 2-H)} 2{μ 2,μ 2-NC 6H 4C 6H 4N}] and [{Os 3(CO) 9(μ 2-H)PPh 3} 2{μ 2,μ 2-NC 6H 4C 6H 4N}]: Carbon–carbon bond formation promoted by organorhodium species

Abstract

Synthesis and characterization of linked cluster [{Os 3(CO) 10(μ 2-H)} 2{μ 2,μ 2-NC 6H 4C 6H 4N}] ( 1) from the reaction of [Os 3Rh(μ-H) 3(CO) 12] with aniline in the presence of an excess amount of 4-vinyl phenol in refluxing heptane is reported. A similar reaction with [Os 3(CO) 10(NCMe) 2] as starting material gave a known compound, [Os 3(CO) 10(μ 2-H)(μ 2-HNC 6H 5)] ( 2). The treatment of complexes 1 and 2 with Wilkinson’s catalyst in refluxing heptane respectively, yielded [{Os 3(CO) 9(μ 2-H)PPh 3} 2{μ 2,μ 2-NC 6H 4C 6H 4N}] ( 3). An interesting and unexpected C–C coupling of phenyl-amido ligands was observed in complexes 1 and 3, which is believed to be catalysed by the organometallic rhodium species. The newly synthesized compounds 1 and 3 were fully characterized by IR, 1H NMR spectroscopy, mass spectroscopy, elemental analysis, and X-ray crystallography. Both structures 1 and 3 comprise two triangles of osmium atoms. The two triangular osmium metal cores are linked by a bi-amido ligand via the two nitrogen atoms N(1) and N(1)* and N(1) and N(2), at their equatorial sites. The electronic absorption spectra of complexes 1, 2, and 3 display both low energy absorption, dπ (Os) → π* (amido) metal-to-ligand charge-transfer (MLCT) transition, and π → π* intra-ligand electronic transitions of the amido and bi-amido ligands.