Formation of a CuII complex through metal-assisted alcoholysis reaction of an oxadiazole-containing dipyridyl ligand: mechanism, characterization and crystal structure

The reaction of 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (L1) with Cu(OAc)2·H2O salt in a CH3OH/CH3CN medium produces a new monometallic copper(II) complex 1 [Cu(L4)(OAc)(H2O)](H2O)2(CH3CN), where HL4 ¼ N-(a-hydroxyl-2-pyridyl)-N0-(a-methoxy-2- pyridyl)ketazine (C13H12N4O2), which was characterized by IR, UV–vis and elemental analysis, and established by X-ray diffraction technique. The results reveal that metal-assisted alcoholysis of L1 leads to the open of the central oxadiazole ring to give a new ligand HL4 during this course. In the crystal structure of complex 1, L4 acts as a tridentate chelating anionic ligand to coordinate to the CuII center, which lies in a square-pyramid coordination environment. Additionally, hydrogen-bonding interactions also play an important role in the selfassembly process. The mechanism of the metal-assisted alcoholysis of L1 in formation of complex 1 was discussed in detail and the spectral properties of 1 were also investigated. q 2004 Elsevier B.V. All rights reserved.