Syntheses, structures and reactivities of [Os₆Pd(CO)₁₈(bipy)] and [{(bipy)Pd}₂Os₃(CO)₁₂]: Crystal and molecular structures of [{(bipy)Pd}₂(μ-H)(μ-CO)][H₃Os₄(CO)₁₂] and [(C₄H₉)₄N]₂[Pd₂I₆]

The complex [(bipy)Pd(CO2Me)2] reacts with [Os3(CO)10(NCMe)2] in a 1:1 molar ratio to give [Os6Pd(CO)18(bipy)] (1) with a moderate yield, and the crystal structure of 1 is presented. Complex 1 is separately treated with an excess of iodine and tetra-n-butylammonium iodide, giving [Os6(CO)18] and [(nBu)4N]2[Pd2I6] (2) respectively. Complex 2 is characterized by X-ray crystallography. The cyclic voltammogram of 1 reveals an irreversible oxidation at a potential of around 0.75 V and no reduction wave is observed. On the contrary, the reaction of [(bipy)Pd(CO2Me)2] with [H2Os3(CO)10] in a 1:2 molar ratio gives [{(bipy)Pd}2Os3(CO)12] (3) with a 25% yield. The X-ray crystallographic study of 3 reveals a stacking situation of the molecules along the c axis. Treatment of 3 with an excess of chloride salt leads to the formation of the cationic species [{(bipy)Pd}2(μ-H)(μ-CO)]+(4) the [H3Os4(CO)12]-salt of which is isolated. Again, a stacking of the dinuclear cations is observed from the X-ray structural analysis of 4.