Date/Time
Date(s) - 11/03/2021
1:30 pm - 2:30 pm

Title:                    Proton- and Structurally-Responsive Ligands for Catalysis 

Date:                   Thursday, March 11th, 2021 

Time:                   1:30 p.m.  

Zoom:                  available from macchem@mcmaster.ca

Host:                    Dr. David Emslie 

Abstract:     

The capacity for ligand structure toinduce unique reactivity is a guiding principle in the field of transitionmetal catalyst design. Beyond stereo-electronic tuning of the metal,cooperative ligands induce reversible changes in the catalyst structure toachieve catalytic turnover.[1] Two cooperative ligand types that we areinvestigating include: proton- responsive ligands that mediate H+ transferor H-bonding interactions, and structurally- responsive ligands that modulatemetal reactivity by changes in ligand coordination mode. Both of these ligandtypes will be covered in this seminar. First, we have demonstrated that[M(Cp/Cp*)(PR2NR’2)(MeCN)]PF6 catalysts(1), where M = Ru, Fe, are active catalysts for the intramolecularhydroamination and hydroalkoxylation of alkynes to selectively afford endo (ratherthan exo) heterocycles.[2] The PR2NR’2 ligand functions to shuttleprotons during the catalytic cycle, which avoids the need for exogenous basesas additives. Performance assessment of catalyst derivatives and mechanisticstudies have revealed optimal structural features to achieve high catalyst performance.The second portion of the presentation will cover the role of astructurally-responsive ligand to enable an unusual Csp3-Csp3 bondformation from 2.[3] The ligand structure contains a1-azaallyl moiety that displays versatile coordination chemistry to support avariety of structures, including bimetallic and monometallic complexes withpalladium in a +2 and +1 oxidation state.

1. [1]  R. H. Crabtree, New J. Chem. 2011, 35, 18-23.
2. [2]  J. M. Stubbs, B. J. Bridge, J. M. Blacquiere, Dalton Trans. 2019, 48, 7928-7937.
3. [3]  K. M. K. Jackman, B. J. Bridge, E. R. Sauve?, C. N. Rowley, C. H. M. Zheng, J. M. Stubbs, P. D. Boyle, J. M. Blacquiere, Organometallics 2019, 38, 1677-1681.