| Popis: |
The synthesis and characterization of an iridium polyhydride complex (Ir-H4)supported by an electron-rich PCP framework is described. This complex readily loses molecularhydrogen allowing for rapid room temperature hydrogen isotope exchange (HIE) at the hydridicpositions and the α-C-H site of the ligand with deuterated solvents such as benzene-d6, toluene-d8and THF-d8. The removal of 1-2 equivalents of molecular H2 forms unsaturated iridium carbenetrihydride (Ir-H3) or monohydride (Ir-H) compounds that are able to create further unsaturationby reversibly transferring a hydride to the ligand carbene carbon. These species are highly activehydrogen isotope exchange (HIE) catalysts using C6D6 or D2O as deuterium sources for thedeuteration of a variety of substrates. By modifying conditions to influence the Ir-Hn speciation,deuteration levels can range from near exhaustive to selective only for sterically accessible sites.Preparative level deuterations of select substrates were performed allowing for procurement of>95% deuterated compounds in excellent isolated yields; the catalyst can be regenerated bytreatment of residues with H2 and is still active for further reactions. |
