A novel trimetallic cluster [Ru5CRh2Pt2(CO)16(dppm)2] was synthesized via coupling of two neutral clusters-[Ru5C(CO)15] and [Rh2Pt2(CO)6(dppm)2]. The structure of this mixed metal complex was established using X-ray crystallography and 31P NMR spectroscopy. It was found that the reaction between [Ru6C(CO)17] and [Pt2(CO)3(dppm)2] leads to spontaneous electron transfer between these polynuclear complexes and results in the formation of an unusually stable cluster "salt" {[Ru6(CO)16]2-[Pt2(CO)2(dppm)2]2+}, which was characterized by crystallographic and spectroscopic methods. Heating of the Ru6-Pt2 ion pair in an autoclave (145 degrees C, 15 atm N2) results in fusion of the metal frameworks to give a nonanuclear mixed metal [Ru6C(CO)16Pt3(dppm)2] cluster in a good yield. The latter complex was obtained earlier as a minor product of another thermal reaction and now has been additionally characterized by 31P NMR spectroscopy.