From M6 to M12, M19 and M38 molecular alloy Pt-Ni carbonyl nanoclusters: selective growth of atomically precise heterometallic nanoclusters

Heterometallic Chini-type clusters [Pt6−xNix(CO)12]2− (x = 0–6) were obtained by reactions of [Pt6(CO)12]2− with Ni-clusters such as [Ni6(CO)12]2−, [Ni9(CO)18]2− and [H2Ni12(CO)21]2−, or from [Pt9(CO)18]2− and [Ni6(CO)12]2−. The Pt/Ni composition of [Pt6−xNix(CO)12]2− (x = 0–6) depended on the nature of the reagents employed and their stoichiometry. Reactions of [Pt9(CO)18]2− with [Ni9(CO)18]2− and [H2Ni12(CO)21]2−, as well as reactions of [Pt12(CO)24]2− with [Ni6(CO)12]2−, [Ni9(CO)18]2− and [H2Ni12(CO)21]2−, afforded [Pt9−xNix(CO)18]2− (x = 0–9) species. [Pt6−xNix(CO)12]2− (x = 1–5) were converted into [Pt12−xNix(CO)21]4− (x = 2–10) upon heating in CH3CN at 80 °C, with almost complete retention of the Pt/Ni composition. Reaction of [Pt12−xNix(CO)21]4− (x ≈ 8) with HBF4·Et2O afforded the [HPt14+xNi24−x(CO)44]5− (x ≈ 0.7) nanocluster. Finally, [Pt19−xNix(CO)22]4− (x = 2–6) could be obtained by heating [Pt9−xNix(CO)18]2− (x = 1–3) in CH3CN at 80 °C, or [Pt6−xNix(CO)12]2− (2–4) in DMSO at 130 °C. The molecular structures of these new alloy nanoclusters have been determined by single crystal X-ray diffraction. The site preference of Pt and Ni within their metal cages has been computationally investigated. The electrochemical and IR spectroelectrochemical behavior of [Pt19−xNix(CO)22]4− (x = 3.11) has been studied and compared to the isostructural homometallic nanocluster [Pt19(CO)22]4−.