Synthesis and organometallic chemistry of new 3-dimensional PC(sp3)P complexes

Over the past 30 years of extensive research, the chemistry and applications of PCP pincer-like complexes have been well documented. These compounds are widely used as homogeneous catalysts and stoichiometric promoters for the challenging chemical transformations, as well as building blocks for the construction of advanced materials. However, the research activity in the field mainly focuses C(sp2)- rather than C(sp3)-based compounds. Recently, we described a new family of C(sp3)-metalated pincer complexes based on dibenzobarrelene scaffold. Unlike most of known PC(sp3)Ps, our compounds are perfectly stable even under very harsh condition, while remain catalytically active. In addition, the suggested scaffold is very modular and three-dimensional. Both these characteristics are remarkably important for diversification of available pincer ligands and fine-tuning chemical/steric/physical properties of the resulting complexes, which makes this class of compounds very attractive for practical applications in many research areas

Applications of the 3-dimensional PC(sp3)P complexes in ligand-metal cooperative catalysis

Molecular complexity of these systems along with coordination versatility of the 3-D sp3-hybridized pincer complexes opens new practical reactivity patterns in non-oxidative (i.e. alternative to the conventional oxidative addition/reductive elimination sequence) activation and formation of polar and non-polar bonds via metal-ligand metal cooperating mechanism. For example, pincer complexes possessing functional sidearm capable of interacting with the catalytic site were identified as practical catalysts in acceptorless dehydrogenation of polar and nonpolar substrates, hydrogenation, hydroformylation, etc.

Chemistry of formic acid

We are interested in the design of novel catalytic systems for dehydrogenation of formic acid/hydrogenation of carbon dioxide and in the development of new generic transformations involving structural modification of functionalized hydrocarbon substrates using formic acid as a source of H2 and CO2. This goal was motivated by the economic and ecological sustainability of formic acid, as well as by importance of fundamental understanding of carbon dioxide interactions with transition metal catalysts. In particular, the catalysts focused in this proposal belong to the family of 3-D bifunctional PC(sp3)P pincer complexes developed in our group in the recent years.