First high-nuclearity palladium halide/carbonyl/phosphine cluster, [Pd12(μ3-I)2(μ4-I)3(μ2-CO)6(PEt3)6]+ monocation containing an octacapped octahedral Pd6(μ3-Pd)6(μ3-I)2 fragment: structure-to-synthesis generation from different synthetic routes

This geometrically unprecedented and unusually stable Pd(+1/2) monocation (1) of crystallographic D3 (32) site symmetry was initially isolated in small yields (<10%), together with two structurally determined square-planar Pd(II) co-products, trans-Pd2 (μ2-I)2I2L2 (7) and trans-PdI2L2 (8) (L = PEt3), and characterized by low-temperature CCD X-ray diffractometry, solid-state/solution IR, and multinuclear (31P, 13C, 1H) NMR measurements. A systematic synthetic exploration involving 14 different chemical reactions demonstrated the importance of conproportionation reactions in increasing the yields of 1 to ca. 50%. Comparative structural/bonding analyses of 1, 7, and 8 with geometrically known analogues are given.