The geometries of the Chini clusters for n=1-8 were determined -see Table and Figure for the explanation of the notion used within, explained on the examples of [Pt3(CO)6] 2-and [Pt3(CO)6]2 2-. Figure in SI illustrates the remaining Chini clusters for n=3-8. While diferent conformers (e.g. "wires", "zigzags", and others) are possible , "wires" are found to be energetically favourable, in agreement with the previous studies . As stated in the introduction, in the Chini clusters two diferent types of the CO ligands are present: terminal and bridging. The length of C-O bonds varies between 1.163 and 1.204 Å, depending on the cluster size and the type of the carbonyl ligand. For the terminal ones, both C-O and Pt-C bonds are slightly shorter (by around 0.02 Å) compared to the bridging ones. The Pt-C bond length ranges from 1.864 to 2.109 Å. The Pt-Pt bond lengths and angles slightly difer, primarily between internal and external Pt3-units. Subsequent Pt3-units are rotated by approximately 16-33°. The intra-triangle Pt-Pt distance ranges from 2.752 to 2.770 Å, while the inter-triangle (Δ-Δ) Pt-Pt distance varies between 3.136 and 3.200 Å. The obtained geometry parameters are in good agreement with the X-ray structures and previous theoretical calculations .