Synthesis of nonanuclear heterometallic carbide clusters. Unexpected formation of the [Ru6(CO)16]2−[Pt2(CO)2(dppm)2]2+ ion pair on the way to [Ru6C(CO)16Pt3(dppm)2]

Abstract

A novel trimetallic cluster [Ru₅CRh₂Pt₂(CO)₁₆(dppm)₂] (3) 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⁺} (1), which was characterized by crystallographic and spectroscopic methods. Heating of the Ru₆–Pt₂ ion pair in an autoclave (145 °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.