Copper(II) complexes with 1,2,4-triazolo[1,5-a] pyrimidine and its 5,7-dimethyl derivative

Several Cu(II) complexes with 1,2,4-triazolo[1,5-alpyrimidine (tp) and its 5,7-dimethyl derivative (dmtp) have been isolated and structurally characterized. Five of them are mononuclear and contain 1, 10-phenanthroline (phen) or ethylenediamine (en) as auxiliary ligands, their formula being [Cu(H2O)-(phen)(tp)(2)](ClO4)(2) - H2O, [Cu(H2O)(phen)(dmtp)(2)](ClO4)(2), [Cu(NO3)(H2O)(phen)(tp)](NO3), (Cu(H2O)(2)-(en)(tp)(2)](ClO4)(2) and [Cu(H2O)(2)(en)(dmtp)(2)](ClO4)(2), In all these compounds the tp or dmtp ligand is monodentately coordinated via the nitrogen atom in position 3. The auxiliary ligand influences the coordination number, which is five when this ligand is phen and six when it is en whereas the number of triazolopyrimidine ligands linked to the metal seems to be influenced by the nature of the counteranion. A dinuclear compound with tp has also been isolated, its formula being [Cu-2(OH)(H2O)(2.5)(tp)(5)]-(ClO4)(3)center dot(H2O)(1.5), with both metal atoms linked by an hydroxydo group and by a tp bridging ligand, coordinated to one of the copper atoms via N3 and to the other via N4. This compound has several unusual features among the metal complexes with triazolopyrimidine derivatives: the presence of two different kinds of bridging moieties, the coexistence of bridging and terminal ligands and the formation of a N3-N4 bridge for a Cu(II) dinuclear compound for a derivative without exocyclic oxygen atoms. (C) 2008 Elsevier Ltd. All rights reserved.