Crystal structure of trans-bis-(7-benzyl-1,3-dimethyl-3,7-di-hydro-1H-purine-2,6-dione)dichloridopalladium(II)...

An air-stable palladium bis-(benzyl-theophylline) complex, [PdCl₂(C₁₄H₁₄N₄O₂)₂]·0.5H₂O, was synthesized from 7-benzyl-theophylline and palladium dichloride. Single-crystal X-ray diffraction analysis revealed that the complex adopts a centrosymmetric structure in which two theophylline ligands coordinate to the square-planar Pd^II center through N atoms on the imidazole ring. The crystal structure contains water mol-ecules located at partially occupied sites (occupancy = 1/4). A notable structural feature is that the fused purine ring system of each ligand is oriented nearly perpendicular to the square-planar Pd^II coordination plane. In addition, the pendant phenyl ring is almost perpendicular to the fused purine ring plane, as indicated by the large torsion angle around the C5-N4-C8-C9 linkage [84.1 (2)°]. These geometric characteristics highlight the steric influence exerted by the benzyl-theophylline ligand on the metal coordination environment.