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The ligand N,N’-dimethylurea (DMU) is used to propagate the octahedral coordination geometry of [Co(DMU)(6)](2+) into 1D and 2D assemblies via a combination of coordinative bonds and interionic hydrogen-bonding. Compounds [Co(DMU)(6)](ClO4)(2) (1), [Co(DMU)(6)](BF4)(2) (2) and [Co(DMU)(6)](NO3)(2) (3) have been prepared from the reactions of DMU and the appropriate hydrated cobalt(II) salts in EtOH, MeCN or Me2CO (only for 1) in the presence of 2,2-dimethoxypropane. Crystal structure determinations demonstrate the existence of [Co(DMU)(6)](2+) cations and ClO4- BF4- or NO3- counterions. The great stability of the [Co(DMU)(6)](2+) cation in the solid state is attributed to a pseudochelate effect which arises from the existence of strong intracationic N-H...O(DMU) hydrogen bonds. The [Co(DMU)(6)](2+) cations and counterions self-assemble to form a hydrogen-bonded 1D architecture in 1, and different 2D hydrogen-bonded networks in 2 and 3. The precise nature of the resulting supramolecular structure is influenced by the nature of the counterion. Two main motifs of intermolecular (interionic) hydrogen bonds have been observed: N-H...O(ClO4-, NO3-) or N-H...F(BF4-) and weak C-H...F(BF4-) or C-H...O(NO3-) hydrogen bonds. The complexes were also characterized by vibrational spectroscopy (IR, far-IR, low-frequency Raman). The spectroscopic data are discussed in terms of the nature of bonding and the known structures.

Reaction of Cu(ClO4)(2). 6H(2)O with 1-methylbenzotriazole (Mebta) in EtOH yields [Cu(Mebta)(4)(H2O)] (ClO4)(2). 0.4EtOH in ca. 75% yield. The structure of this salt has been determined by single-crystal X-ray crystallography. Mebta behaves as a monodentate ligand binding through N(3). The metal coordination geometry is best described as distorted square pyramidal with the H2O ligand occupying the apical site. The complex was also characterized by molar conductivity, room-temperature effective magnetic moment and spectroscopic (i.r., far-i.r., u.v./vis, e.s.r.) studies. The data are discussed in terms of the nature of bonding and known structure. Comparison between the structural and spectroscopic properties of [Cu(Mebta)(4)(H2O)](ClO4)(2). 0.4EtOH and those of the (CuI)-I-I site of Cu-Zn superoxide dismutase shows that the former can be considered as a fairly good model for the latter. Transition Metal Chemistry

Reaction of Cu(ClO4)(2). 6H(2)O with 1-methylbenzotriazole (Mebta) in EtOH yields [Cu(Mebta)(4)(H2O)] (ClO4)(2). 0.4EtOH in ca. 75% yield. The structure of this salt has been determined by single-crystal X-ray crystallography. Mebta behaves as a monodentate ligand binding through N(3). The metal coordination geometry is best described as distorted square pyramidal with the H2O ligand occupying the apical site. The complex was also characterized by molar conductivity, room-temperature effective magnetic moment and spectroscopic (i.r., far-i.r., u.v./vis, e.s.r.) studies. The data are discussed in terms of the nature of bonding and known structure. Comparison between the structural and spectroscopic properties of [Cu(Mebta)(4)(H2O)](ClO4)(2). 0.4EtOH and those of the (CuI)-I-I site of Cu-Zn superoxide dismutase shows that the former can be considered as a fairly good model for the latter.