Synthesis of [{Os3(CO)10(μ2-H)}2{μ2,μ2-NC6H4C6H4N}] and [{Os3(CO)9(μ2-H)PPh3}2{μ2,μ2-NC6H4C6H4N}]: Carbon–carbon bond formation promoted by organorhodium species

Abstract

Synthesis and characterization of linked cluster [{Os3(CO)10(μ2-H)}2{μ2,μ2-NC6H4C6H4N}] (1) from the reaction of [Os3Rh(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 [Os3(CO)10(NCMe)2] as starting material gave a known compound, [Os3(CO)10(μ2-H)(μ2-HNC6H5)] (2). The treatment of complexes 1 and 2 with Wilkinson’s catalyst in refluxing heptane respectively, yielded [{Os3(CO)9(μ2-H)PPh3}2{μ2,μ2-NC6H4C6H4N}] (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.