Dinuclear nickel(II) complexes of reduced asymmetric compartmental ligands

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)(mu-OAc) (OH2)(CH3OH)][PF6], 2, [Ni2L4(mu-OAc)2(CH3OH)][PF6], 3, [Ni2L4(mu-OAc)2(OH2)(CH3OH)][PF6], 4, and [Ni2L4(muOAc)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.