Studies on metal complexes of isocytosine derivative: The crystal structure of zinc(II) complex of 2-hydrazino-4-hydroxy-6-methylpyrimidine.

Abstract

The crystal structure of the copper (II) complex of 2-hydrazino-4-hydroxy-6-methylpyrimidine (LH) has been determined from three-dimensional X-ray diffractometer data by heavy atom Fourier methods. Crystals of [Cu (LH)2 (H2O)] Cl2·2H2O are triclinic with unit cell dimensions a=10.020 (2), b=14.384 (2), c=7.205 (1) A, α=104.63 (2)°, β=111.04 (1)°, γ=84.93 (2)°, space group P 1, and Z=2. Block-diagonal least-squares refinement using 3126 independent reflections yielded an R value of 0.062. There are two mirror-image complex molecules in a unit cell. Each copper (II) complex has five coordinated bonds and assumes a distorted square pyramid structure. The two ligand molecules, (LH)2 are trans coordinated to the copper (II) ion through nitrogen atoms N3 of the pyrimidine rings and also through the amino nitrogen atoms of the hydrazino groups. In each copper (II) complex, the one apical coordination site is occupied by the water oxygen atom. The hydroxyl group at C4 of the pyrimidine ring takes the keto form, since the hydrogen atom of the hydroxyl group transfers to N1 of the ring. The chloride ions are not directly hydrogen bonded to the N1 atoms of the pyrimidine bases, but are bound to the apical water oxygen atoms. The pyrimidine rings in the crystals are not stacked in parallel but are inclined at an angle of 18.9 or 18.8°.