Synthesis and structure of isocytosine ternary copper(II) complexes†

Abstract

The ternary complexes (glycylglycinato)(isocytosine)copper(II) dihydrate 1 and (glycylglycinato)(6-methylisocytosine)copper(II) monohydrate 2 have been prepared and characterised by X-ray diffraction, electrochemistry and optical, ESR and IR spectroscopy. The two compounds are slightly distorted square planar, with the four co-ordination sites occupied by the tridentate glycylglycine dianion [O(7), N(13) and N(10)] and N(3) of the pyrimidine base. An additional weak axial interaction exists between an oxygen of a water molecule O(W1) and the copper atom [Cu· · ·O(W1) distances 2.74 and 2.70 Å respectively]. Spectroscopic and electrochemical data are in accord with the crystal structures. Although both compounds exhibit irreversible oxidation processes, the oxidation of Cu^II to Cu^III is best performed with the isocytosine complex.