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({6,6′-[(ethane-1,2-diylbis(methylazanediyl)]bis(methylene)}bis(2,4-di-tert-butylphenol))palladium(II) chlorido(2,4-di-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(methylene)}bis(2,4-di-tert-butylphenol))palladium(II), {(L 2)PdCl2}, and chlorido(2,4-di-tert-butyl-6-{[(2-{[(3,5-di-tert-butyl-2-hydroxyphenyl)methyl](methyl)amino}ethyl)(methyl)amino]methyl}phenolato)palladium(II), {(L 2 X)PdCl}, molecules as well as fractional water and methanol solvent molecules.