Palladium(II) complexes of a bridging amine bis(phenolate) ligand featuring κ2 and κ3 coordination modes

Abstract

Bidentate and tridentate coordination of a 2,4-di-tert-butyl-substituted bridging amine bis(phenolate) ligand to a palladium(II) center are observed within the same crystal structure, namely dichlorido({6,60-[(ethane-1,2-diylbis(methylaza-nediyl)]bis(methylene)}bis(2,4-di-tert-butylphenol))palladium(II) chlorido(2,4di-tert-butyl-6-{[(2-{[(3,5-di-tert-butyl-2-hydroxyphenyl)methyl](methyl)amino}-ethyl)(methyl)amino]methyl}phenolato)palladium(II) methanol 1.685-solvate 0.315-hydrate, [PdCl2(C34H56N2O2)][PdCl(C34H55N2O2)]∙1.685CH3OH∙-0.315H2O. Both complexes exhibit a square-planar geometry, with unbound phenol moieties participating in intermolecular hydrogen bonding with co-crystallized water and methanol. The presence of both κ2 and κ3 coordination modes arising from the same solution suggest a dynamic process in which phenol donors may coordinate or dissociate from the metal center, and offers insight into catalyst speciation throughout Pd-mediated processes. The unit cell contains dichlorido({6,6'-[(ethane-1,2-diylbis(methylazanediyl)]bis(methyl-ene)}bis(2,4-di-tert-butylphenol))palladium(II), {(L2)PdCl2}, and chlorido(2,4di-tert-butyl-6-{[(2-{[(3,5-di-tert-butyl-2-hydroxyphenyl)methyl](methyl)amino}-ethyl)(methyl)amino]methyl}phenolato)palladium(II), {(L2X)PdCl}, molecules as well as fractional water and methanol solvent molecules.