Synthesis and Characterisation of a Hterobimetallic N-heterocyclic Carbene Rhodium Ruthenium Complex as Catalyst for Transfer Hydrogenation

The heterobimetallic N-heterocyclic dicarbene (NHDC) rhodium ruthenium complex [Ru(OAc)(Mes-NHC-methyl-PPh2)(Mes-aNHC-methyl-PPh2)RhCl(cod)] ( 4 ) is obtained from a mixed normal/abnormal bis-NHC ruthenium complex via transmetallation by addition of [RhCl(cod)](2) in THF at 40 degrees C, applying Ag2O as base. Crystallization is achieved by layering a solution of 4 in THF with Et2O. The complex is applicable as a catalyst in the transfer hydrogenation (TH) reaction of acetophenone, exhibiting a turnover frequency (TOF) of 6 700 h(-1) with 80% conversion after 25 min (0.10 mol% catalyst, (PrOH)-Pr-i, 80 degrees C, 2.00 mol% (NaOPr)-O-i). These results are compared to an analogous iridium ruthenium NHDC complex. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The heterobimetallic N-heterocyclic dicarbene (NHDC) rhodium ruthenium complex was synthesized via transmetallation and tested as a catalyst in the transfer hydrogenation reaction of acetophenone. The complex exhibited high turnover frequency and good catalytic performance.