Octaboraneyl bis(diphosphine)nickel(II)-hydride complexes: exploiting phosphine ligand lability for hydride transfer
Author ORCID Identifier
https://orcid.org/0000-0001-6903-5787 : Joseph A. Zurakowski
Standing
Graduate (Masters)
Type of Proposal
Oral Research Presentation
Faculty Sponsor
Dr. Marcus W. Drover
Proposal
Chemists are fascinated by the connectivity of atoms. As synthetic chemists, we place focus on joining atoms in new ways to create molecules that display useful and interesting behaviours. Our research begins with ligand design - a central tenet of synthetic chemistry. A ligand makes chemical bonds to a metal atom, creating a unique environment for the metal and supporting it throughout a particular chemical reaction. Simple modification of a specific ligand can lead to major differences in reactivity at the metal atom. Herein, we describe the divergent reactivity of two bis(diphosphine)nickel(II) complexes with pendant boranes in the secondary coordination sphere, [Ni(H)(P2BR4)2]+ (R = Cy or Mes; Mes = 2,4,6-trimethylphenyl). Divergent reactivity of the cyclohexyl analogue toward the [NAD]+ model, 3-acetyl-N-benzylpyridinium ([BNAcP]Br), is underscored. While [Ni(H)(P2BCy4)2]+ undergoes rapid hydride transfer, the related “all-alkyl” species [Ni(H)(dnppe)2]+ [dnppe = 1,2-bis(di-n-propylphosphino)ethane] and adduct [Ni(H)(P2BCy4)2(DMAP)8]+ (DMAP = 4-N,N-dimethylaminopyridine) exhibit no such reactivity. This borane appended nickel(II) hydride provides future opportunities for the design of [Ni(H)(diphosphine)2]+ reagents for productive and unique hydride transfer. As well, the ligand lability of P2BCy4 is underscored as an important step for successful hydride transfer. This work represents an important foray into the area of ligand design by modification of the secondary coordination sphere.
Availability
Mar 29: all day; Mar 30, Noon-1300; Mar 31, not available; Apr 1; Noon-1300
Octaboraneyl bis(diphosphine)nickel(II)-hydride complexes: exploiting phosphine ligand lability for hydride transfer
Chemists are fascinated by the connectivity of atoms. As synthetic chemists, we place focus on joining atoms in new ways to create molecules that display useful and interesting behaviours. Our research begins with ligand design - a central tenet of synthetic chemistry. A ligand makes chemical bonds to a metal atom, creating a unique environment for the metal and supporting it throughout a particular chemical reaction. Simple modification of a specific ligand can lead to major differences in reactivity at the metal atom. Herein, we describe the divergent reactivity of two bis(diphosphine)nickel(II) complexes with pendant boranes in the secondary coordination sphere, [Ni(H)(P2BR4)2]+ (R = Cy or Mes; Mes = 2,4,6-trimethylphenyl). Divergent reactivity of the cyclohexyl analogue toward the [NAD]+ model, 3-acetyl-N-benzylpyridinium ([BNAcP]Br), is underscored. While [Ni(H)(P2BCy4)2]+ undergoes rapid hydride transfer, the related “all-alkyl” species [Ni(H)(dnppe)2]+ [dnppe = 1,2-bis(di-n-propylphosphino)ethane] and adduct [Ni(H)(P2BCy4)2(DMAP)8]+ (DMAP = 4-N,N-dimethylaminopyridine) exhibit no such reactivity. This borane appended nickel(II) hydride provides future opportunities for the design of [Ni(H)(diphosphine)2]+ reagents for productive and unique hydride transfer. As well, the ligand lability of P2BCy4 is underscored as an important step for successful hydride transfer. This work represents an important foray into the area of ligand design by modification of the secondary coordination sphere.