Nucleophilic Palladium Carbenes Utilizing Metal-Ligand Cooperativity Towards Small Molecule Activations

Transition-metal carbenes have long been known to exhibit unique reactivity and utilized in a wide variety of applications including synthetic methods for the production of natural products, materials (polymerizations), and are invoked as intermediates in many important chemical industrial processes. Our efforts are to isolate various elusive carbene complexes, similar to those thought to be involved in important palladium catalytic processes, and to broaden the horizons of reactivity invoked by transition-metal carbenes. The reactivity studies focused on inert small molecule activations essential for more sustainable and renewable energy sources, continued improvements to chemical feedstock production methods and employment of feedstocks in the synthesis of higher value chemicals.

With this intention, the synthesis and characterization of various ligand scaffolds (PCP_ipr, PCP_tbu, PC_ph, PC_ph, PCN, PCO) was accomplished by our group and metalated on palladium centers. The previously synthesized PCP palladium carbenes were reacted with a variety of small molecules, in this work: ammonia, nitrobenzene, and nitrosobenzene will be discussed in detail. With the emergence of interesting late-transition metal bimetallic chemistry, synthetic methods for the production of bimetallic group 10 metals was of interest to us as well. Our focus was to explore reactivity of the carbene complexes and attempt to synthesize related palladium carbene complexes to expand the scope of reactivity with a special focus on the effects of metal ligand cooperativity.