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 [Pt-6(CO)(12)](2-) with Ni-clusters such as [Ni-6(CO)(12)](2-), [Ni-9(CO)(18)](2-) and [H2Ni12(CO)(21)](2-), or from [Pt-9(CO)(18)](2-) and [Ni-6(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 [Pt-9(CO)(18)](2-) with [Ni-9(CO)(18)](2-) and [H2Ni12(CO)(21)](2-), as well as reactions of [Pt-12(CO)(24)](2-) with [Ni-6(CO)(12)](2-), [Ni-9(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 degrees C, with almost complete retention of the Pt/Ni composition. Reaction of [Pt12-xNix(CO)(21)](4-) (x approximate to 8) with HBF4 center dot Et2O afforded the [HPt14+xNi24-x(CO)(44)](5-) (x approximate to 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 degrees C, or [Pt6-xNix(CO)(12)](2-) (2-4) in DMSO at 130 degrees 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 [Pt-19(CO)(22)](4-).