RhI-complexes of ditopic bis(pyrazol-1-yl)borate ligands: Assessment of their catalytic activity towards phenylacetylene polymerization

Novel ditopic 1,4-phenylene-bridged bis(pyrazol-1-yl)borate ligands have been used for the synthesis of dinuclear RhI-cyclooctadiene complexes [1,4-(cod)Rh(B(R′)pz2)-C6H4-(B(R′)pz2)Rh(cod)] (R′ = Ph, C6F5; pz = pyrazolide). Treatment of the related 3-phenylpyrazolyl-substituted discorpionates [1,4-(B(R′)pz2Ph)-C6H4-(B(R′)pz2Ph)]2- with Rh2Cl2(cod)2 did not lead to the formation of the corresponding RhI-complexes but gave the compound [(cod)Rh(μ-pzPh)2Rh(cod)] which proved to be an efficient catalyst for the preparation of highly stereoregular head-to-tail cis-transoidal poly(phenylacetylene).