Dinuclear nickel(ii) complexes of reduced asymmetric compartmental ligands

Abstract

The reaction of the reduced asymmetric compartmental proligand 2-{[(2-dimethylaminoethyl)ethylamino]methyl}-4-methyl-6-{[(pyridin-2-ylmethyl)amino]methyl}phenol, HL⁴ with nickel(II) acetate in the presence of non-coordinating anions gave dinuclear nickel(II) complexes. The crystal structures of [Ni₂L⁶(OAc)(μ-OAc)(OH₂)(CH₃OH)][PF₆], 2, [Ni₂L⁴(μ-OAc)₂(CH₃OH)][PF₆], 3, [Ni₂L⁴(μ-OAc)₂(OH₂)(CH₃OH)][PF₆], 4, and [Ni₂L⁴(μ-OAc)₂(CH₃OH)₂][BPh₄], 5, are reported. 2-[(2-Dimethylaminoethylamino)methyl]-6-{[(2-dimethylaminoethyl)ethylamino]methyl}-4-methylphenol, HL⁵, was found to react with Ni(ClO₄)₂·4H₂O and NaBPh₄ in the presence of urea. to give [Ni₂L⁵(OH)(OH₂)₂(urea)][BPh₄]₂, 6, the dinuclear core of which bears some resemblance to that of the active site in urease. The crystal structure reveals the presence of a hydroxo-bridge and an O-bonded molecule of urea.