1,1′-(1-Propene-1,3-diyl)-ferrocene: modified synthesis, crystal structure, and polymerisation behaviour

The dehydro[3](1,1′)ferrocenophanes, 1,1′-(1-propene-1,3-diyl)-ferrocene (3a), and 1,1′-(3-phenyl-1-propene-1,3-diyl)-ferrocene (3b) were synthesised under Shapiro conditions from the tosylhydrazones of the corresponding α-oxo-[3](1,1′)ferrocenophanes. Electrochemistry shows 3a is oxidised at smilar potential to ferrocene; according 3a can be chemically oxidised using silver trifluoromethanesulfonate. The structure of 3a shows a ring tilt of 11.3°. Attempts to polymerise 3a using the ROMP initiator Mo(CHCMe2Ph)[N(2,6-iPr2C6H3)][OCMe(CF3)2]2 led to a mixture of insoluble material and a soluble mixture of apparently cyclic oligomers ([3a]n).