Hydrogen-Bonded Networks Based on Cobalt(II) Nickel(II) and Zinc(II) Complexes of NN-Diethylurea

摘要

N,N'-diethylurea (DEU) was employed as a ligand to form the octahedral complexes [M(DEU)6]²⁺ (M=Co, Ni and Zn). Compounds [Co(DEU)6](BF4)2 (>1), [Co(DEU)6](CIO4)2 (>2), [Ni(DEU)6](CIO4)2 (>3), and [Zn(DMU)6](CIO4)2 (>4) have been prepared from the reactions of DEU and the appropriate hydrated metal(II) salts in EtOH in the presence of 2,2-dimethoxypropane. Crystal structure determinations demonstrate the existence of [M(DEU)6]²⁺ cations and CIO4 ⁻ (in >2–4) or BF4 ⁻ (in >1) counterions. The [M(DEU)₆]²⁺ cations in the solid state are stabilized by a pseudochelate effect due to the existence of six strong intracationic N-H ⋯ O_(DEU) hydrogen bonds. The [M(DEU)₆]²⁺ cations and counterions self-assemble to form hydrogen-bonded 2D architectures in >2–4 that conform to the >kgd (kagome dual) network, and a 3D hydrogen-bonded >rtl (rutile) network in >1. The nature of the resulting supramolecular structures is influenced by the nature of the counter-ion. The complexes were also characterized by vibrational spectroscopy (IR).