title: Oxygen binding to [Pd(L)(L')] (L= NHC, L' = NHC or PR3, NHC = N-heterocyclic carbene). synthesis and structure of a paramagnetic trans-[Pd(NHC)2(η(1)-O2)2] complex.
abstract: The reactivity of a number of two-coordinate [Pd(L)(L')] (L = N-heterocyclic carbene (NHC) and L' = NHC or PR(3)) complexes with O(2) has been examined. Stopped-flow kinetic studies show that O(2) binding to [Pd(IPr)(P(p-tolyl)(3))] to form cis-[Pd(IPr)(P(p-tolyl)(3))(η(2)-O(2))] occurs in a rapid, second-order process. The enthalpy of O(2) binding to the Pd(0) center has been determined by solution calorimetry to be -26.2(1.9) kcal/mol. Extension of this work to the bis-NHC complex [Pd(IPr)(2)], however, did not lead to the formation of the expected diamagnetic complex cis-[Pd(IPr)(2)(η(2)-O(2))] but to paramagnetic trans-[(Pd(IPr)(2)(η(1)-O(2))(2)], which has been fully characterized. Computational studies addressing the energetics of O(2) binding have been performed and provide insight into reactivity changes as steric pressure is increased.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Cai
authors.forename: Subhojit
authors.initials: S
authors.lastname: Majumdar
authors.forename: George C
authors.initials: GC
authors.lastname: Fortman
authors.forename: Catherine S J
authors.initials: CS
authors.lastname: Cazin
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.forename: Charles
authors.initials: C
authors.lastname: Lhermitte
authors.forename: Rajeev
authors.initials: R
authors.lastname: Prabhakar
authors.forename: Meaghan E
authors.initials: ME
authors.lastname: Germain
authors.forename: Taryn
authors.initials: T
authors.lastname: Palluccio
authors.forename: Steven P
authors.initials: SP
authors.lastname: Nolan
authors.forename: Elena V
authors.initials: EV
authors.lastname: Rybak-Akimova
authors.forename: Manuel
authors.initials: M
authors.lastname: Temprado
authors.forename: Burjor
authors.initials: B
authors.lastname: Captain
authors.forename: Carl D
authors.initials: CD
authors.lastname: Hoff