Macrocyclic Di- and Tetranuclear Osmacycloferrocenophanes^†^,1

The novel dinuclear and tetranuclear ortho-, meta-, and para-osmacycloferrocenophanes [η5-C5H4(CH2)n-1,m-C6H4(CH2)nOs(CO)4(CH2)n-1,m-C6H4(CH2)nC5H4-η5]xFex (n = 2−4, m = 2−4; x = 1: 3a−h; x = 2: 4a−h) have been made available by the reaction of the corresponding bis(triflates) [η5-C5H4(CH2)n-1,m-C6H4(CH2)nOTf]2Fe (2a−h) with Na2[Os(CO)4] in refluxing dimethyl ether. The macrocycles of 3b,c,e and 4a,h were investigated by X-ray structural analyses and consist of an extended hydrocarbon skeleton containing additionally two and four transition metal centers, respectively. In the case of the dinuclear osmacycloferrocenophanes 3a−h the redox behavior was examined by means of cyclic voltammetry, and the results were compared with those of the bis(alcohols) 1a−h, which were used as starting compounds for the bis(triflates) 2a−h. With increasing chain length the ferrocene unit is easier oxidized, and in the case of 3f−h the E1/2 values are in the region of diethylferrocene.