Premium
Electronic Support Effects of Tunable Mixed Metal Oxides on Immobilized Palladium N‐Heterocyclic Carbene Complexes
Author(s) -
Finn Matthew T.,
Donahue Courtney M.,
Blake Anastasia V.,
An Nan,
Daly Scott R.,
VoutchkovaKostal Adelina M.
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800220
Subject(s) - chemistry , x ray photoelectron spectroscopy , xanes , palladium , electronegativity , metal , binding energy , inorganic chemistry , spectroscopy , catalysis , organic chemistry , physics , nuclear magnetic resonance , quantum mechanics , nuclear physics
Electronic effects of supports on site‐isolated organometallic complexes are poorly understood, despite indication that such effects impact stability and reactivity of immobilized complexes. Here we report X‐ray photoelectron spectroscopy (XPS) and X‐ray absorption near edge structure (XANES) spectroscopy studies of surface‐immobilized Pd II N‐heterocyclic carbene complexes on Mg‐Al mixed metal oxides (MMOs) using silane‐modified ligands. XPS revealed a ca. 1 eV increase in Pd binding energy as a result of immobilization on MMOs, suggesting that the Pd II complex becomes more electropositive when appended to the surface. For MMOs doped with Fe, Ni, Co and Zn, analysis of Cl K‐edge and Pd L 2 ‐ and L 3 ‐edge showed increasing pre‐edge energies that followed the order Fe = Ni < Zn = Cr < undoped Mg‐Al MMO. The Pd L 3 pre‐edge energies correlated to the calculated oxygen partial charge of the MMO, as estimated using the Sanderson electronegativity model. Transmission electron microscope images collected on the immobilized Pd complexes revealed nanoparticles on three of the five MMOs, whose presence can be related to the Pd XPS and XANES energies. These findings suggest that electronic differences associated with the MMO supports impact the stability of appended Pd II complexes with respect to reduction to Pd 0 .