Chloro-bridged oligomers of the type [Pt(amine)Cl-2](n), have been synthesized and characterized by IR and H-1- and Pt-195-NMR spectrometry. These compounds are believed to consist of mostly dimers in the solid state. Heating the oligomers in dichloromethane solution favors the formation of trimers. The crystal structure of the dimethylamine chloro-bridged trimer was determined by X-ray diffraction. The crystals belong to the trigonal (hexagonal cell) R (3) over bar space group, with a = 15.463(6) Angstrom, c = 13.984(5) Angstrom, and Z = 6. The results have shown that the compound is a cyclic six-membered chloro-bridged trimer with a 3-fold axis in the center of the ring. The terminal Pt-Cl bond is 2.274(3) Angstrom, significantly shorter than the bridging bonds which are 2.332(3) and 2.319(3) Angstrom. The Pt3Cl3 ring assumes a "crown" conformation with C-3 symmetry. The internal angles are Cl-Pt-Cl’ = 90.5(1)degrees and Pt-Cl-Pt’ = 93.9(2)degrees. The oligomers are rapidly cleaved in DMF to form first cis-Pt(amine)(DMF)Cl-2, which isomerize to the trans isomers. On standing in acetone or dichloromethane solution, the DMF complexes are partly rearranged to the chloro-bridged oligomers. A few iodo-bridged oligomers were characterized by Pt-195 NMR. The resonances of these species were observed around -4000 ppm. Contrary to the chloro-bridged compounds, the iodo complexes are not cleaved by DMF.