A single-site olefin polymerization catalyst is described. The catalyst comprises an activator and an organometallic compound that includes a Group 3 to 10 transition or lanthanide metal, M, and a modified boraaryl ligand. We surprisingly found that the catalyst is more active in olefin polymerization compared to other catalysts containing non-modified boraaryl ligands. Most surprisingly, the supported catalyst gives polyolefins with a multimodal molecular weight distribution having separate components of distinct molecular weight.