Studies on the linkage isomers of ambidentate ligands are increasingly important in molecular dynamical materials. Such results have been extended beyond the initial studies to diverse areas as quantum mechanical calculations, molecular switches, isomeric catalysts, the design of therapeutic reagents, the imaging agents in the body, and the separation of diastereomers. Although the coordination modes of ambidentate ligands may be vaguely predicted via electronic and steric effects, the coordination modes are sensitive to various factors such as central metals, oxidation states, coligands, reaction time, temperature, the solvent properties, etc. In some cases, the steric factor plays an important role in determining the relative stability of the linkage isomers. According to a previous report, an isomerism between the (O,O')and (O,alkene)-chelates was observed for diallylmalonatoplatinum(II) complexes. In order to scrutinize the coligand effects on the coordination chemistry of similar ambidentate ligands in platinum(II) complexes, benzyl-1-propenylmalonate (BPM) has been used as an anionic ambidentate ligand in this work. The ligand may coordinate to the platinum atom via either (O,O') or (O,alkene) mode. N,N,N',N'-Tetramethylethylenediamine (TMEDA), N,N'-dimethylethylenediamine (DMEDA), and ethylenediamine (en) were employed in order to examine the coligand effects on the coordination chemistry of BPM. Here we report the synthesis and structural properties of new platinum(II) complexes.