Syntheses, Structures, and Electrochemistry of the Defective ccp [Pt33(CO)38](2-) and the bcc [Pt40(CO)40](6-) Molecular Nanoclusters.
The molecular [Pt33(CO)38](2-) nanocluster was obtained from the thermal decomposition of Na2[Pt15(CO)30] in methanol. The reaction of [Pt19(CO)22](4-) with acids (1-2 equiv) affords the unstable [Pt19(CO)22](3-) trianion, which evolves with time leading eventually to the [Pt40(CO)40](6-) hexa-anion. The total structures of both nanoclusters were determined via single-crystal X-ray diffraction. [Pt33(CO)38](2-) displays a defective ccp Pt33 core and shows that localized deformations occur in correspondence of atomic defects to "repair" them. In contrast, [Pt40(CO)40](6-) shows a bcc Pt40 core and represents the largest Pt cluster with a body-centered structure. The rich electrochemistry of the two high-nuclearity platinum carbonyl clusters was studied by cyclic voltammetry and electrochemical in situ Fourier transform infrared spectroscopy. The redox changes of [Pt33(CO)38](2-) show features of chemical reversibility and electrochemical quasi-reversibility, and the vibrational spectra in the CO stretching region of the nine redox forms of the cluster [Pt33(CO)38](n) (n = 0 to -4, -6 to -9) are reported. Almost all the redox processes exhibited by [Pt40(CO)40](6-) are chemically and electrochemically reversible, and the eight oxidation states of [Pt40(CO)40] from -4 to -11 were spectroscopically characterized. The effect of the more regular bcc Pt-carbonyl cluster structure of [Pt40(CO)40](6-) with respect to that of the defective ccp Pt33 core on the redox behavior is discussed.
Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, 40136 Bologna, Italy.
Enrico
E
Cattabriga
Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, 40136 Bologna, Italy.
Iacopo
I
Ciabatti
Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, 40136 Bologna, Italy.
Cristina
C
Femoni
Dipartimento di Chimica e Chimica Industriale, University of Pisa , Via Moruzzi 13, 56124 Pisa, Italy.
Tiziana
T
Funaioli
Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, 40136 Bologna, Italy.
Maria Carmela
MC
Iapalucci
Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, 40136 Bologna, Italy.
Stefano
S
Zacchini