Synthesis, multinuclear magnetic resonance and crystal structures of Pt(II) complexes containing amines and bidentate carboxylate ligands

A novel synthetic method for the synthesis of the complexes cis-Pt(amine)2R(COO)2 is compared to two other methods involving the use of either barium dicarboxylate or sodium carboxylate. Pt(II) compounds with monodentate and bidentate amines were studied. The reaction involves the use of a silver dicarboxylato complex, which is the intermediate in the new synthetic procedure. The crystal structure of the silver intermediate with the ligand 1,1-cyclobutanedicarboxylate (1,1-CBDCA) was determined by X-ray diffraction. The crystal Ag2(1,1-CBDCA) has a very interesting 3-D extended structure. The complexes cis-Pt(amine)2R(COO)2 were studied in solution by multinuclear (1H, 13C and 195Pt) magnetic resonance spectroscopy, but the solubilities are very low. D2O was found to be the best solvent. In 195Pt NMR, the complexes containing bidentate amines forming five-membered chelates were observed at higher fields than those containing monodentate amines. The resonances of the NH3 compounds were also found at lower fields than the primary amine complexes. All the dicarboxylato ligands form six-membered chelates except 1,2-CBDCA, whose Pt(II) compounds were observed at lower fields than the others. The crystal structures of Pt(en)(1,1-CBDCA), Pt(Meen)(1,1-CBDCA) and Pt(en)(benzylmalonato) were confirmed by X-ray diffraction methods. Several compounds are disordered. The crystals are stabilized by intermolecular hydrogen bonds between the –NH2 groups and the carboxylato O atoms.

A novel synthetic method for the synthesis of Pt(II) complexes of the type cis-Pt(amine)2R(COO)2 is reported. The compounds were characterized by multinuclear (195Pt, 1H and 13C) magnetic resonance spectroscopy. The crystal structure of a silver intermediate Ag2(1,1-cyclobutyldicarboxylato) has shown that the compound has an extended structure with metal–metal bonds. The crystal structure of three complexes Pt(amine)2R(COO)2 especially with ethylenediamine derivatives are reported.Figure optionsDownload as PowerPoint slide