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

Treatment of [N(PPh 3 ) 2 ][1,3,6-{Re(CO) 3 }-3,6-( μ -H) 2 -1,1-(CO) 2 -2-Ph- closo -1,2-IrCB 9 H 7 ] ( 2a ) with {Cu(PPh 3 )} + gives two types of polymetallic species: [1,4,7-{Cu(PPh 3 )}-1,5,6-{Re(CO) 3 }-4,5,6,7-( μ -H) 4 -1,1-(CO) 2 -2-Ph- c loso -1,2-IrCB 9 H 5 ] ( 4a ), containing a V-shaped Re−Ir−Cu trimetallic unit, and [1,3,6-{Cu 2 (PPh 3 ) 2 }-3,6-( μ -H) 2 -1,1-(CO) 2 -2-Ph- closo -1,2-IrCB 9 H 7 ] ( 5a ), containing an IrCu 2 triangle. In contrast, [N(PPh 3 ) 2 ][1,3,6-{Re(CO) 3 }-3,6-( μ -H) 2 -1,1-(CO) 2 -2-Ph- closo -1,2-RhCB 9 H 7 ] ( 2b ) with the same copper cation essentially affords only the corresponding RhCu 2 species 5b . Reaction of 2a with {Au(PPh 3 )} + yields up to three types of polymetallic species, namely, [1,6-{Au 2 (PPh 3 ) 2 }-6-( μ -H)-1,1-(CO) 2 -2-Ph- closo -1,2-IrCB 9 H 8 ] ( 7a ), which contains an IrAu 2 triangle and is thus related to compounds 5, [1,3,6-{Au 2 (PPh 3 ) 2 Re(CO) 3 }-6-( μ -H)-1,1-(CO) 2 -2-Ph- closo -1,2-IrCB 9 H 7 ] ( 8a ), in which there is an {Au 2 IrRe} “butterfly” arrangement of metal atoms that is supported by the carborane, and the tetrametallic [1,3-{Au 3 (PPh 3 ) 3 }-1,1-(CO) 2 -2-Ph- closo -1,2-IrCB 9 H 8 ] ( 9a ), which contains an Au 3 triangle bonded to the iridacarborane. The parallel reaction of 2b with {Au(PPh 3 )} + gives up to four polymetallic products: these are compounds 7b, 8b, and 9b, the rhodium-containing analogues of 7a, 8a, and 9a, respectively, along with the trimetallic [8,9,10- endo -{Au(PPh 3 )}-3,4,8- exo -{Re(CO) 3 }-3,4-( μ -H) 2 -8,8-(CO) 2 -7-Ph- nido -8,7-RhCB 9 H 7 ] ( 6b ), which has a V-shaped Re−Rh−Au unit and a nido -structured rhodacarborane core.