Metal complexes of purine-N-oxides. II. The crystal structure of catena-μ-(4-aminoimidazole-5-carboxamidoxime) diaquo copper(II) sulphate trihydrate, a degradation product of adenine-N1-Oxide

Abstract

[Cu(C4H7N5O)H2O)2SO4]·3H2O, monoclinic, space group Cc, a = 13.652(1) Å, b = 14.630(1) », c = 6.795(1) », β = 95.34(8)°, Z = 4. 1479 independent intensities above background were collected on a CAD-4 diffractometer using MoKα radiation. The structure was refmed by full-matrix least-squares to R = 0.016. Adenine-N1-oxide is degraded at a higher pH than expected when Cu ions are present. The degradation product is formed by scission of the C2N1 and C2N3 bonds. N1 is placed in a cis planar configuration to N7 by a rotation around the C5C6 bond, thus enabling N1, N7 equatorial chelation to copper, which has a 4 + 2 octahedral coordination. Two water molecules occupy the remaining equatorial positions, while the axial positions are occupied by a sulphate group and N3 of an adjacent ligand. The coordination bond lengths are CuN1 = 1.960 », CuN7 = 1.972 », CuO2 = 1.949 », CuO4 = 1.987 », CuO9 = 2.500 », CuN3 = 2.793 ».