Angel García-Raso, Juan J. Fiol, Bartomeu Adrover, Virtudes Moreno, Elies Molins and Ignasi Mata
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 CuII to CuIII is best performed with the isocytosine complex.