The use of ruthenium complexes in transvinylation catalysis has been well established since the 1980s. However, the reaction mechanism and the active catalyst species, which is presumed to contain ruthenium carbonyl carboxylate entities, have so far remained elusive. In this work the synthesis and characterization of three novel ruthenium complexes comprising ruthenium carbonyl carboxylate structural motifs including two single crystal structures as well as the crystal structures of two known ruthenium complexes are reported. These new complexes and four known ruthenium complexes with appropriate structural motifs were applied in transvinylation catalysis. Mechanistic studies including identification and characterization of the active species, isotope labeling experiments and examination of the regio‐ and stereoselectivity of the transvinylation reaction are presented, resulting in the proposal of a probable reaction mechanism, which is supported by DFT calculations on the B3LYP/6‐31G* level of theory.magnified image

The reaction of Ru 3 (CO) 12 with pivalic or propionic acid leads to the formation of two novel multinuclear ruthenium complexes, [Ru 4 (CO) 8 (μ-OOCCH 2 CH 3 ) 4 (THF) 2 ] (1) and [Ru 3 (μ 3 -OH)(CO) 6 (μ-OOC t Bu) 4 (OOC t Bu)] (2). Compound 1 is among the few examples of discrete tetranuclear ruthenium compounds showcasing a "dimer of dimers" paddlewheel structure, in which two "Ru 2 (CO) 4 (μ-OOCCH 2 CH 3 ) 2 (THF)" fragments are linked via Ru−O interactions. Compound 2 features a unique structural motif in which a triangular Ru 3 core is connected via a μ 3 -OH ligand. Note pubs.acs.org/Organometallics