Synthesis of conjugated oligomers and polymers: the organometallic way
Results of special interest in the field of organometallic chemistry directed towards the synthesis of conjugated oligomers and polymers are reviewed. Methodologies widely employed in the synthesis of well-defined molecules and based on the transition metal catalyzed coupling reactions of various organometallic (B, Sn, Si, Mg and Zn) reagents have been more recently extended to build up poly- or oligo-meric conjugated molecular architectures. Although the focus of the present work is on transition metal cross-coupling or homo-coupling processes, other useful organometallic routes, such as metathesis reactions and acetylene polymerization, have also been dealt with. Owing to their higher versatility with respect to the non-organometallic processes commonly used for the synthesis of these materials, the approaches presented allow the realization of more complex molecular structures, which are nowadays required in many electronic and optoelectronic applications. The use of organometallic strategies has been discussed from a synthetic organic chemist's point of view, and advantages and limitations of the different methodologies reviewed have been highlighted. Some attention has also been paid to the properties of the resulting materials and to their dependence on the procedure followed and the framework obtained.