Synthesis and structural studies on new M IIX 2L 2 dihalocomplexes of 1-methyllumazine and 1,6,7-trimethyllumazine. : Crystal structure of copper(II) and palladium(II) complexes

Abstract

In order to continue our studies in coordination chemistry with pteridine derivatives, four new complexes with general formula M IIX 2(pteridine) 2· nH 2O· mCH 3CN (M=Cu, Pd, Pt) have been synthesized by reaction of 1-methyllumazine (MLM) and 1,6,7-trimethyllumazine (MLMD) and different halide salts in acetonitrile solutions. These compounds have been characterized by means of analytical techniques (elemental analysis and TG), spectral methods (IR, 13C and 1H NMR, UV–Vis–NIR, EPR) and magnetics measurements. Single-crystal X-ray diffraction studies have been developed on the [CuCl 2(MLM) 2] and [PdBr 2(MLM) 2] complexes. In the complex Cu/MLM, a six-coordinated environment around metal ion is shown, with two pteridine ligands behaving in a bidentante manner through N5/O4 atoms being the other positions occupied by two chlorine atoms. The molecular unit of the compound Pd/MLM shows an ion Pd(II) linking to two bromide ions placed in a trans position, and two N5 atoms of two organic ligands, exhibiting a square-planar geometry as it is usual in complexes with d 8-configuration ions.