Degradation of urea mediated by dinickel(II) complexes with the binucleating ligand N,N′-bis[2-(N,N-dimethyl)aminoethyl]-N,N′-dimethyl-1,3-diamino-2-hydroxypropane (HL)

A new urea-coordinated dinickel(II) complex, [Ni2L(μ-Cl)(μ-urea)(urea)2](BPh4)2 (2), was synthesized. Investigation of urea degradation mediated by complex 2 in a nitromethane/ethanol solution containing a small amount of water revealed the formation of a novel tetranuclear nickel(II) complex, [{Ni2L(μ-carbamato)}2(μ-NCO)2] (BPh4)2·(CH3NO2)4 (3). X-ray crystallography revealed that in complex 3, two dinuclear nickel(II) units containing two nickel(II) ions linked by carbamate ions were further bridged by isocyanate ions and by the carbamate ions acting as a tetradentate ligand. The complex 3 and the related tetranuclear nickel(II) complexes, [{Ni2L(μ-Cl)}2(μ-NCO)2](BPh4)2 (4) and [{Ni2L(μ-ureato)}2(μ-Cl)2](BPh4)2·(DMF)2 (5), gave new information for assuming the mechanism of urea degradation mediated by the dinuclear nickel(II) complex.