Formation and Characterization of the Hexanuclear Platinum Cluster [Pt6(-PBut2)
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- 作者：Fabrizia Fabrizi de Biani ; Andrea Ienco ; Franco Laschi ; Piero Leoni ; Fabio Marchetti ; Lorella Marchetti ; Carlo Mealli ; and Piero Zanello
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：March 9, 2005
- 年：2005
- 卷：127
- 期：9
- 页码：3076 - 3089
- 全文大小：371K
- 年卷期：v.127,no.9(March 9, 2005)
- ISSN：1520-5126
文摘
The reaction between equimolar amounts of Pt3(
-PBut2)3(H)(CO)2, Pt3H, and CF3SO3H underCO atmosphere affords the triangular species [Pt3(-PBut2)3(CO)3]X, [Pt3(CO)3+]X (X = CF3SO3-),characterized by X-ray crystallography, or in an excess of acid, [Pt6(-PBut2)4(CO)6]X2, [Pt62+]X2. Structuraldetermination shows the latter to be a rare hexanuclear cluster with a Pt4 tetrahedral core formed by joiningthe unbridged sides of two orthogonal Pt3 triangles. The dication Pt62+ features also extensive redoxproperties as it undergoes two reversible one-electron reductions to the congeners [Pt6(-PBut2)4(CO)6]+(Pt6+, E1/2 = -0.27 V) and Pt6(-PBut2)4(CO)6 (Pt6, E1/2 = -0.54 V) and a further quasi-reversible two-electron reduction to the unstable dianion Pt62- (E1/2 = -1.72 V). The stable radical (Pt6+) and diamagnetic(Pt6) species are also formed via chemical methods by using 1 or 2 equiv of Cp2Co, respectively; furtherreduction of Pt62+ causes fast decomposition. The chloride derivatives [Pt6(-PBut2)4(CO)5Cl]X, (Pt6Cl+)X,and Pt6(-PBut2)4(CO)4Cl2, Pt6Cl2, observed as side-products in some electrochemical experiments, wereprepared independently. The reaction leading to Pt3(CO)3+ has been analyzed with DFT methods, andidentification of key intermediates allows outlining the reaction mechanism. Moreover, calculations for thewhole series Pt62+ 
Pt62- afford the otherwise unknown structures of the reduced derivatives. While theprimary geometry is maintained by increasing electron population, the system undergoes progressive andconcerted out-of-plane rotation of the four phosphido bridges (from D2d to D2 symmetry). The bonding atthe central Pt4 tetrahedron of the hexanuclear clusters (an example of 4c-2e- inorganic tetrahedral aromaticityin Pt62+) is explained in simple MO terms.
-PBut2)3(H)(CO)2, Pt3H, and CF3SO3H underCO atmosphere affords the triangular species [Pt3(-PBut2)3(CO)3]X, [Pt3(CO)3+]X (X = CF3SO3-),characterized by X-ray crystallography, or in an excess of acid, [Pt6(-PBut2)4(CO)6]X2, [Pt62+]X2. Structuraldetermination shows the latter to be a rare hexanuclear cluster with a Pt4 tetrahedral core formed by joiningthe unbridged sides of two orthogonal Pt3 triangles. The dication Pt62+ features also extensive redoxproperties as it undergoes two reversible one-electron reductions to the congeners [Pt6(-PBut2)4(CO)6]+(Pt6+, E1/2 = -0.27 V) and Pt6(-PBut2)4(CO)6 (Pt6, E1/2 = -0.54 V) and a further quasi-reversible two-electron reduction to the unstable dianion Pt62- (E1/2 = -1.72 V). The stable radical (Pt6+) and diamagnetic(Pt6) species are also formed via chemical methods by using 1 or 2 equiv of Cp2Co, respectively; furtherreduction of Pt62+ causes fast decomposition. The chloride derivatives [Pt6(-PBut2)4(CO)5Cl]X, (Pt6Cl+)X,and Pt6(-PBut2)4(CO)4Cl2, Pt6Cl2, observed as side-products in some electrochemical experiments, wereprepared independently. The reaction leading to Pt3(CO)3+ has been analyzed with DFT methods, andidentification of key intermediates allows outlining the reaction mechanism. Moreover, calculations for thewhole series Pt62+ Pt62- afford the otherwise unknown structures of the reduced derivatives. While theprimary geometry is maintained by increasing electron population, the system undergoes progressive andconcerted out-of-plane rotation of the four phosphido bridges (from D2d to D2 symmetry). The bonding atthe central Pt4 tetrahedron of the hexanuclear clusters (an example of 4c-2e- inorganic tetrahedral aromaticityin Pt62+) is explained in simple MO terms.