Comparison of theophyllinato Cu(II) complexes of ethanolamine and diethanolamine Part 2. Structure and thermal study of the dimeric complex with diethanolamine

Madarász, János and Bombicz, Petra and Czugler, Mátyás and Pokol, György (2000) Comparison of theophyllinato Cu(II) complexes of ethanolamine and diethanolamine Part 2. Structure and thermal study of the dimeric complex with diethanolamine. POLYHEDRON, 19 (4). pp. 457-463. ISSN 0277-5387

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Abstract

There is now much evidence that anticancer drugs exert biological action by preferred binding of a transition metal to the N7 sites of the guanine residues of DNA. In our series of theophyllinato copper(II) complexes containing amine ligands, the structural effect of changing from ethanolamine to diethanolamine is examined. A new mixed ligand copper(II) complex, bis(mu-2-(2-hydroxyethyl) aminoethanolato-O,N,O') bis(theophyllinato-N7) dicopper(II) (C22H34N10O8Cu2) (1) has been synthesized as model compound from aqueous solutions of CuSO4, theophylline, and diethanolamine (dea). Its distinct Me2L2L'(2) structure has been determined by single crystal X-ray diffraction. The centrosymmetric binuclear complex contains two strongly distorted square pyramidally (or pseudo-octahedrally) coordinated copper ions bound together by two alkoxo-bridges. The bridging O is a deprotonated oxygen of the monoalcoholate formed from diethanolamine. Both of the theophyllinate anions take part in N7/O6 chelation in the complex 1, while only one of the theophyllinate anions is able to perform it in the mononuclear complex (SPY-5-12)-(2-aminoethanol-N) (2-aminoethanol-N,O)bis(theophyllinato-N7)copper(II) dihydrate(2). The two copper(II) centres in 1 are found to be antiferromagnetically coupled. The combined thermogravimetric and evolved gas detection shows that the tridentate alcoholate anions are fragmented and evolved between 125 and 275 degrees C, whilst the degradation of theophyllinate anions begins at 350 degrees C. Structural, spectroscopic and thermal comparison to the previously published analogous monoethanolamine Cu(II) complex (2) is presented. (C) 2000 Elsevier Science Ltd All rights reserved.

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