Exploring the Effect of Pincer Rigidity on Oxidative Addition Reactions with Cobalt(I) Complexes
- 5 April 2023
- journal article
- research article
- Published by American Chemical Society (ACS) in Organometallics
- Vol. 42 (8) , 708-718
Abstract
Cobalt complexes containing the 2,6-diaminopyridine-substituted PNP pincer (iPrPNMeNP = 2,6-(iPr2PNMe)2(C5H3N)) were synthesized. A combination of solid-state structures and investigation of the cobalt(I)/(II) redox potential established a relatively rigid and electron-donating chelating ligand as compared to iPrPNP (iPrPNP = 2,6-(iPr2PCH2)2(C5H3N)). Based on a buried volume analysis, the two pincer ligands are sterically indistinguishable. Nearly planar, diamagnetic, four-coordinate complexes were observed independent of the field strength (chloride, alkyl, aryl) of the fourth ligand completing the coordination sphere of the metal. Computational studies supported a higher barrier for C-H oxidative addition, largely a result of the increased rigidity of the pincer. The increased oxidative addition barrier resulted in stabilization of (iPrPNMeNP)Co(I) complexes, enabling the characterization of the cobalt boryl and the cobalt hydride dimer by X-ray crystallography. Moreover, (iPrPNMeNP)CoMe served as an efficient precatalyst for alkene hydroboration likely because of the reduced propensity to undergo oxidative addition, demonstrating that reactivity and catalytic performance can be tuned by rigidity of pincer ligands.Keywords
Funding Information
- Kwanjeong Educational Foundation
- Alexander von Humboldt-Stiftung
- National Institute of General Medical Sciences (GM121441)
This publication has 89 references indexed in Scilit:
- Formal loss of an H radical by a cobalt complex via metal–ligand cooperationChemical Communications, 2013
- Synthesis and Protonation of Molybdenum– and Tungsten–Dinitrogen Complexes Bearing PNP-Type Pincer LigandsOrganometallics, 2012
- An OCO3–Trianionic Pincer Tungsten(VI) Alkylidyne: Rational Design of a Highly Active Alkyne Polymerization CatalystJournal of the American Chemical Society, 2012
- Modularly Designed Transition Metal PNP and PCP Pincer Complexes based on Aminophosphines: Synthesis and Catalytic ApplicationsAccounts of Chemical Research, 2008
- Highly Active Iridium Catalysts for Alkane Dehydrogenation. Synthesis and Properties of Iridium Bis(phosphine) Pincer Complexes Based on Ferrocene and RuthenoceneOrganometallics, 2006
- Chiral palladium bis(phosphite) PCP-pincer complexes via ligand C–H activationChemical Communications, 2006
- Silica and polymer-tethered Pd?SCS-pincer complexes: evidence for precatalyst decomposition to form soluble catalytic species in Mizoroki?Heck chemistryJournal of Catalysis, 2004
- A Pd complex of a tridentate pincer CNC bis-carbene ligand as a robust homogenous Heck catalystChemical Communications, 2001
- Influence of Coordination Geometry upon Copper(II/I) Redox Potentials. Physical Parameters for Twelve Copper Tripodal Ligand ComplexesInorganic Chemistry, 1999
- Transition metal–carbon bonds. Part XLII. Complexes of nickel, palladium, platinum, rhodium and iridium with the tridentate ligand 2,6-bis[(di-t-butylphosphino)methyl]phenylJ. Chem. Soc., Dalton Trans., 1976