Diruthenium tetracarbonyl sawhorse complexes bearing N-heterocylic carbene and phosphine ligands: Synthesis, structural characterization, and catalytic activity

A number of dinuclear ruthenium(I) sawhorse complexes substituted with an N-heterocyclic carbene or various phosphine ligands have been prepared and characterized by FT-IR, NMR, and elemental analysis. Treatment of [Ru-2(mu-O2CCH3)(2)(CO)(4)](n) with 2-electron donating ligands (L) yields the dimeric derivatives Ru-2(m-O2CCH3)(2)(CO)(4)L-2, where L = IMes [1,3-bis(2,4,6-trimethylphenyl) imidazol-2-ylidene] (1), P(o-CH3C6H4)(3) (2), P(C6F5)(3) (3), P(c-C6H11)(3) (4), and P(C6H5)(3) (5). The syntheses of 1-3 are reported herein; the syntheses of 4 and 5 have been previously reported. The crystal structures of 1-3 have been determined by single crystal X-ray diffraction. Factors influencing the structures of 1-5 are discussed and compared to DFT calculated geometries. An initial assay of the catalytic activities of 1-5, employing the isomerization of 1-hexene, has been performed. (C) 2015 Elsevier B.V. All rights reserved.