Chromium Complexes with Acenaphthene Imine Derivative Ligands Synthesis and Catalysis on Diene Polymerization

Treatment of the bis(arylimino)acenaphthene (BIAN) ligands with CrCl2(THF)2 in THF affords mononuclear complexes of ArBIANCrCl2(THF)2 (3a, Ar = 2-iPrC6H4; 3b, Ar = 2,6-Me2C6H3) and chlorine-bridging dinuclear complexes ArBIANCrCl(μ-Cl)3Cr(THF)ArBIAN (3c, Ar = 2,6-Et2C6H3; 3d, Ar = 2,6-iPr2C6H3). The molecular structures of 3b–3d were characterized by X-ray diffraction analysis, and all the chromium atoms are in octahedral geometries. Similar reactions of N-(arylimino)acenaphthenones with CrCl2(THF)2 afford the dinuclear chromium complexes with 1,1′-bis(2-aryliminoacenaphthene-1-olate) tetradentate ligands ArBIAOCr2Cl4(THF)2 (4b, Ar = 2,6-Me2C6H3; 4c, Ar = 2,6-Et2C6H3) via a pinacol cross-coupling reaction. Upon activation with MAO, these complexes show moderate-to-high activities in butadiene and isoprene polymerization, affording a cis-1,4-enriched polymer.