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

• The first diruthenium tetracarbonyl sawhorse NHC adduct is reported.
• An assay of catalytic ability, mild conditions, reveals a distinctly active complex.
• DFT calculations were performed to support experimental results.
• Phosphine cone angles, as achieved in the solid-state, have been calculated.

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 [Ru2(μ-O2CCH3)2(CO)4]n with 2-electron donating ligands (L) yields the dimeric derivatives Ru2(μ-O2CCH3)2(CO)4L2, 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.

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