摘要 : Stoichiometric reaction of CoCO3. Co(OH)(2). 2H(2)O, or NiCO3. 2Ni(OH)(2). 4H(2)O with H(2)ADA and imidazole (Him) in water yields crystalline samples of compounds aqua(imidazole)(N-carbamoylmethyl-iminodiacetato)metal(II), [M(ADA... 展开 Stoichiometric reaction of CoCO3. Co(OH)(2). 2H(2)O, or NiCO3. 2Ni(OH)(2). 4H(2)O with H(2)ADA and imidazole (Him) in water yields crystalline samples of compounds aqua(imidazole)(N-carbamoylmethyl-iminodiacetato)metal(II), [M(ADA)(Him)(H2O)].1.5H(2)O (M = Co, compound I, dark pink: M = Ni, compound II, bluish). Single-crystal X-ray diffraction studies were carried out. Both complexes are isostructural (orthorhombic system, space group Pna2(1), Z = 8). These crystals consist of slightly asymmetrical octahedral coordination units linked in a tridimensional network stabilised by hydrogen bonds when all N-H bonds of ADA and Him and probably O-H bonds of water molecules are involved. The asymmetric unit has two independent but very similar complex molecules and three water ones. Coordination bond distances for I (average in Angstrom): Co-N(amino) = 2.14(1), Co-O(carboxyl) = 2.06(1), Co-O(carboxyl) = 2.08(1) and Co-O(amide) = 2.15(1) with ADA, Co-N(Him)= 2.04(1), and Co-O(aqua) = Coordination bond lengths for II (average in Angstrom): Ni-N(amino) = 2.08(1), Ni-O(carboxyl) = 2.04(1), Ni-O(carboxyl) = 2.06(1) and Ni-O(amide) = 2.012(1) with ADA, Ni-N(Him) = 2.01(1), and Ni-O(aqua) = 2.12(1). The ADA ligand acts as a tripodal tetradentate chelating one. On the basis of the octahedral structures of [Ni(ADA)(H2O)(2)], reported in the literature, and of the new compounds, it is concluded that there is a preference for the N(Him)donor atom to occupy the trans-position to the M-N(ADA) bond. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 58] 收起