Speakers

CO and CO2 Activation at a Single Nickel Center

2
Yunho Lee
Korea Advanced Institute of Science and Technology
Nov. 1 11:35~12:00

Abstract

Adduct formations of the 1st row transition metals with small molecules such as carbon monoxide and carbon dioxide are drawing much attention due to their importance in developing synthetic catalysts for various industrial processes. In our laboratory, a series of such species are currently under investigation to show their respective roles in small-molecule transformations that include carbon dioxide transformation for modeling ACS/CODH active site chemistry and carbon monoxide conversion as a key step for Fisher-Tropsch synthesis. In this presentation, a particular study with low-valent nickel complexes will be discussed. Synthesis and characterization of a four coordinate (PEP)Ni-L scaffold (E = N, P or Si), where a L site is occupied by a ligand such as NHR2, N2, CO, CO2 or COOR will be described. A series of Ni-CO2 adducts and analogous species based on a (PEP)Ni scaffold have been generated revealing unique binding character to a low-valent nickel center. In particular, a 5-coordinate nickel(0) species (PPMeP)Ni(η2-CO2) and a cationic square planar nickel(II) complex {(PNP)Ni(η1-CO2)}+ will be presented regarding binding and activation of CO2. The first example of a heterobimetallic Ni-CO2-Fe species will be also discussed, of which structural and electronic features are related to those of a Ni-μ-CO2-Fe fragment found in CODH. The relationship between the binding modes of CO2 and the degree of CO2 activation will be addressed by comparing Ni-η1-CO2C, Ni-μ-CO2-Fe and previously reported Ni-η2-CO2 complexes. Regarding the geometry and reactivity relationship, tetrahedral and square planar nickel complexes will be discussed. A (PPP)M scaffold reveals the interconversion between square planar and tetrahedral geometry in which reversible alkoxy group transfer occurs between a phosphide moiety of a PPP ligand and a nickel ion via unanticipated metal-ligand cooperation. This unusual group transfer reaction is tightly coupled with metal’s local geometry and its 0/II redox couple. In contrast, a (PNP)M scaffold shows a selective reaction pattern occurring at the structurally rigidified nickel center. Unique open-shell reactivity of a T-shaped nickel(I) metalloradical supported by a rigid acridane-based pincer ligand will be discussed.
References

  1. “A T-Shaped Ni(I) Metalloradical Species” Angew. Chem., Int. Ed. 2017, 56, 9502.
  2. 2. “Carbon Dioxide Binding at a Ni/Fe Center; Synthesis and Characterization of Ni(η12-κC) and Ni-μ-CO<2C2O,O’-Fe” Chem. Sci. 2017, 8, 600.
  3. 3. “Formation of a Nickel Carbon Dioxide Adduct and its Transformation Mediated by a Lewis Acid” Chem. Commun. 2014, 50, 11458.
  4. 4. “Transmethylation of a Four-Coordinate Nickel(I) Monocarbonyl Species with MeI” Chem. Sci. 2014, 5, 3853.

 

Education

  • 2001-2007, Ph.D. The Johns Hopkins University (Inorganic Chemistry)

 

Professional Career

  • 2015-Present, Associate Professor, KAIST
  • 2010-2015, Assistant Professor, KAIST
  • 2007-2010, Postdoctoral Associate, MIT and CalTech

 

Awards and Honors

  • 2017, KCS-Wiley Young Scholar Award, KCS
  • 2013, 2015, 2017, Excellent Teaching Award, College of Natural Sciences, KAIST
  • 2015, Young Inorganic Chemist Award, KCS
  • 2012, The Distinguished Lectureship Award, the Chemical Society of Japan