Facile Synthesis of Linear and Cyclic Poly(diphenylacetylene)s by Molybdenum and Tungsten Catalysis.

Improved methods for the synthesis of linear and cyclic poly(diphenylacetylene)s by polymerization of the corresponding diphenylacetylenes using MoCl - and WCl -based catalytic systems have been developed. MoCl induces migratory insertion polymerization of diphenylacetylenes in the presence of arylation reagents such as Ph Sn and ArSn Bu to produce cis-stereoregular linear poly(diphenylacetyelene)s with high molecular weights (number-average molar mass (M )=30,000-3,200,000) in good yields (up to 98 %). On the other hand, WCl induces ring expansion polymerization of diphenylacetylenes in the presence of Ph Sn or reducing reagents to produce cis-stereoregular cyclic poly(diphenylacetylene)s with high molecular weights (M =20,000-250,000) in moderate to good yields (up to 90 %). Both catalytic systems are applicable to the polymerization of various diphenylacetylenes having polar functional groups such as esters that are not efficiently polymerized by conventional methods using WCl -Ph Sn and TaCl - Bu Sn systems.