The role of amide ligands in the stabilization of Pd(II) tricoordinated complexes: Is the Pd-NR2 bond order single or higher?

Salvador Moncho Escriva, Gregori Ujaque, Pablo Espinet, Feliu Maseras, Agustí Lledós

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The existence of tricoordinated Pd(II) complexes has been a matter of controversy for a long time. The recent X-ray characterization of a family of Pd complexes [PdArXL] allowed to certify the existence of true tricoordinated Pd(II) species. The unique role played by the amido ligand (X = NR2), among a family of X ligands, was noticed in a previous computational work. Here, the influence of the R substituents at the amide and the nature of the Pd-Namido bond are theoretically analyzed. The relative stability of d 8 tricoordinated [PdLAr(NR2)] complexes versus d 8 tetracoordinated derivatives as a function of the R substituents is studied by analyzing the two most common ways to fill the vacant coordination site in a tricoordinated complex: solvent coordination (with tetrahydrofuran as solvent), or dimerization giving [(μ-NR2)2Pd 2L2Ar2]) complexes. The nature of the Pd-N bonding interaction is analyzed using several theoretical schemes as molecular orbitals, QTAIM, ELF and NBO. Each of these schemes suggests that the order of the Pd-N bond in this family of complexes is higher than one. An asymmetric π interaction between the nitrogen lone pair and the LUMO over the tricoordinated Pd center is proposed as an important source of additional stabilization of tricoordinated species provided by amido ligands.

Original languageEnglish
Pages (from-to)75-84
Number of pages10
JournalTheoretical Chemistry Accounts
Issue number1-2
Publication statusPublished - May 2009
Externally publishedYes



  • Amide ligands
  • Palladium chemistry
  • Theoretical transition metal chemistry

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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