Arene complexes ring-opening metathesis polymerization

It has been shown that [(r]6-arene)RuCl2]2 6 and [(r 6-arene)RuCl2] PR3 7 complexes can be activated in situ to afford active metathesis catalysts, either on treatment with diazoalkanes [15] or by UV irradiation [16]. The structure of the active species thus formed is unknown, but it initiates the ring opening metathesis polymerization reactions (ROMP) of various cycloalkenes very efficiently. Therefore these in situ recipes may also be useful in the context of preparative organic chemistry. 

The ring-opening metathesis polymerization of norbomene monomers functionalized with arene complexes of cyclopentadienyliron has been reported using Grubbs catalyst. These polymerization reactions proceeded rapidly to produce the corresponding polynorbomenes (32 and 33). It was found that the incorporation of bulkier aromatic groups in the sidechains of these materials increased their glass transition temperatures and thermal stability. 

We have reported that norbornene monomers functionalized with arene complexes also undergo ring-opening metathesis polymerization to produce the corresponding cyclopentadienyliron-coordinated polynorbomenes. Scheme 13 shows the synthesis of polymers containing aromatic ether sidechains functionalized with organoiron moieties. ... 

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