Construction of Metal Butterflies on a Metallacarborane Scaffold. 2. Synthesis and Structures of Hetero-tri- and -tetrametallic Clusters

Treatment of [N(PPh3)2][1,3,6-{Re(CO)3}-3,6-(μ-H)2-1,1-(CO)2-2-Ph-closo-1,2-IrCB9H7] (2a) with {Cu(PPh3)}+ gives two types of polymetallic species:  [1,4,7-{Cu(PPh3)}-1,5,6-{Re(CO)3}-4,5,6,7-(μ-H)4-1,1-(CO)2-2-Ph-closo-1,2-IrCB9H5] (4a), containing a V-shaped Re−Ir−Cu trimetallic unit, and [1,3,6-{Cu2(PPh3)2}-3,6-(μ-H)2-1,1-(CO)2-2-Ph-closo-1,2-IrCB9H7] (5a), containing an IrCu2 triangle. In contrast, [N(PPh3)2][1,3,6-{Re(CO)3}-3,6-(μ-H)2-1,1-(CO)2-2-Ph-closo-1,2-RhCB9H7] (2b) with the same copper cation essentially affords only the corresponding RhCu2 species 5b. Reaction of 2a with {Au(PPh3)}+ yields up to three types of polymetallic species, namely, [1,6-{Au2(PPh3)2}-6-(μ-H)-1,1-(CO)2-2-Ph-closo-1,2-IrCB9H8] (7a), which contains an IrAu2 triangle and is thus related to compounds 5, [1,3,6-{Au2(PPh3)2Re(CO)3}-6-(μ-H)-1,1-(CO)2-2-Ph-closo-1,2-IrCB9H7] (8a), in which there is an {Au2IrRe} “butterfly” arrangement of metal atoms that is supported by the carborane, and the tetrametallic [1,3-{Au3(PPh3)3}-1,1...