Cu(II) halide and primary amine complexes of guanine and xanthine

Abstract

Guanine (Gua) and xanthine (Xan) complexes of copper halides of types Cu(Gua)Cl 2 Cu(Gua)Br 2, Cu(Xan) 2Cl 2·2H 2O and Cu(Xan) 2Br 2 were synthesized by the interaction of the ligand and respective metal halide in methanol. In addition, Cu(Guan)(CH 3NH 2) 2·2H 2O and Cu(Xan)(CH 3NH 2) 2·2H 2O were prepared by reacting CuSO 4·5H 2O with the respective purine in the indicated primary amine. IR spectra of the halide complexes suggest that their stereochemistry is distorted tetrahedal, in keeping with previously reported complexes of this type. The amine compounds exhibit significant carbonyl IR shifts, indicating hydrogen bonding is present between purine carbonyl and the primary amine. Room-temperature magnetic susceptibilities are normal for related Cu(II) complexes. Comparison of these compounds with known complexes suggests the possibility of N(7)–N(9) purine bridging between copper atoms leading to polymer formation.