SYNTHESIS AND CHARACTERIZATION OF THE CENTERED ICOSAHEDRAL CLUSTER SERIES [AU(9)M(4)(IB)CL(4)(PMEPH(2))(8)][C2B9H12] WHERE M(IB)=AU, AG OR CU

The compounds [Au(9)M(4)(IB)Cl(4)(PMePh(2))(8)][C2B9H12](M(IB) = Au, A g or Cu) have been prepared from solutions of [Au-11(PMePh(2))(10)][C2 B9H12](3) by the addition or formation in situ of [M(IB)Cl(PMePh(2))]. The reaction is believed to take place via the intermediate cations [ Au(11)M(2)(IB)Cl(2)(PMePh(2))(10)](3+) and [Au(10)M(3)(IB)Cl(3)(PMePh( 2))(9)](2+) The final products have been characterized by FAB mass spe ctrometry, electronic spectroscopy and P-31-{H-1}, B-11-{H-1} and H-1 NMR spectroscopy. Single-crystal X-ray diffraction studies on [Au9Ag4C l4(PMePh(2))(8)]-[C2B9H12]. H2O . 0.5CH(2)Cl(2) and [Au9Cu4Cl4(PMePh(2 ))(8)][C2B9H12]. CH2Cl2 have been carried out. The cations of these co mpounds contain centred icosahedral metal frameworks and in both cases the cages have approximate C-2v symmetry: the silver and copper atoms , associated with the halide ligands, occupy identical positions. A go ld atom sits at the interstitial site; The cations cannot be Superimpo sed due to differences in the ligand packing. Comparable Au-Au bond le ngths in the two structures are very similar and, given the large diff erences that are seen between the Au-Ag and the Au-Cu bond lengths, th e Ag-CI and Cu-CI moieties can be visualized as moving relative to one another along radial vectors.