Copper(II)-assisted hydrolysis of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt): syntheses, crystal structures and magnetic properties of [Cu(bpcam)(H2O)(2)]ClO4 center dot 3H(2)O, [Cu(bpcam)(H2O)(2)] [Cu(bpcam)(H2O)(SO4)] center dot 2H(2)O and [Cu-

摘要

The reaction of the 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt) ligand with copper(II) perchlorate or sulfate in aqueous solution affords complexes [Cu(bpcam)(H2O)(2)]ClO4-3H(2)O (1), [Cu(bpcam)(H2O)(2)][Cu(bpcam)(H2O)(SO4)]center dot 2H(2)O (2) and [Cu-2(bpcam)(2) (H2O)(2)(SO4)] center dot H2O (3) [bpcam = bis(2-pyrimidylcarbonyl)amidate], whose structures have been determined by single-crystal X-ray diffraction studies. Copper(II) promotes the hydrolysis of tpymt in mild conditions yielding the bpcam group which is present in the structures of 1-3 as a tridentate ligand. The structure of 1 consists of mononuclear [Cu(bpcam)(H2O)(2)](+) cations, uncoordinated perchlorate anions and water of crystallization. The structure of 2 is made up of [Cu(bpcam)(H2O)(2)](+) cations, [Cu(bpcam)(H2O)(SO4)](-) anions and lattice water whereas that of 3 contains the neutral dinuclear complex [Cu-2(bpcam)(2) (H2O)(SO4)] and lattice water. While the sulfate group act as a terminal monodentate ligand in 2, it adopts a bis-monodentate bridging mode in 3. The copper atom coordination sphere in 1-3 is distorted square pyramidal, with three bpcam nitrogen atoms (1-3) and a water molecule (1 and 2) or a sulfate oxygen (2 and 3) building the basal plane and another water molecule (1-3) in the apical position. The values of the shortest intermolecular copper-copper separation in 1 and 2 are 5.705 and 6.604 angstrom, respectively, whereas that through bridging sulfato in 3 is 5.494 angstrom. Variable-temperature magnetic susceptibility measurements show a Curie law behaviour for 2 whereas a weak intramolecular antiferromagnetic interaction [J = -7.0 cm(-1), the Hamiltonian being defined as (H) over cap = -J (S) over cap (1) center dot (S) over cap (2)] occurs in 3. The potential use for metal assembling of the stable mononuclear [Cu(bpcam)](+) unit is discussed in the light of the results obtained with the related [Cu(bpca)](+) complex [bpca = bis(2-pyridylcarbonyl)amidate]. (c) 2004 Elsevier B.V. All rights reserved.