Inorganic Seminar Series

Seminar series
Inorganic Chemistry
Wed, Feb 27 4:30pm
3440 Mol Sci
Speaker Prof. Francois Gabbai
Texas A&M University
Department of Chemistry

Pairing antimony Lewis acids with late transition metals: Applications in organometallic catalysis

Abstract: Controlling the reactivity of transition metal (M) catalysts by secondary coordination sphere effects is an active area of active investigation with applications in catalysis. The functionality installed in the secondary coordination sphere of a metal center can be Lewis basic, in which case it serves to engage electrophilic reaction substrates. It can also be a hydrogen-bond donor group which can help with the stabilization of anionic intermediates, such as those generated during a reduction reaction. A less explored area of research concerns the use of Lewis acidic functionalities which, in principle, could serve in a capacity similar to those of hydrogen-bond donor groups. Lewis acidic functionalities, when positioned sufficiently close to the metal center, can enter its primary coordination sphere leading to a direct metal-Lewis acid interaction. In such instances, the Lewis acid behaves as a Z-type ligand and draws on the electron density of the metal center. The formation of this interaction provides a handle over the electron density of the metal center and offers unique opportunities in the realm of catalysis. In this presentation, we will describe the synthesis and properties of platinum and gold complexes in which an antimony atom acts as a Z-type ligand. Such pnictogen-based Z-type ligands are attractive because of their tunability which can be achieved by III/V redox switching or by anion exchange at the antimony center. These processes can be used to strengthen the M -> Sb interaction and, in turn, augment the electrophilic reactivity of the late transition metal center. These changes come to bear on reactions involving not only alkynes but also alkenes, thus opening the door to new opportunities in organometallic catalysis.