Dedicated to Dr Karel Mach on the occasion of his 70th birthday, in appreciation of his substantial contribution to the organometallic chemistry of early transition metals and for his gracious hospitality extended to visitors to "the golden city" of Prague.Lithium 2,5-bis{ [(2,6-diisopropylphenyl) . The molecular structures of 1 and 2 have been determined by X-ray diffraction. The structure of 2 is unusual in that it features weak, but equivalent interactions of both imine groups of the η 1 -pyrrolide ligands with the chromium, giving rise to an approximately octahedral coordination geometry with two extremely long Cr-N distances. Keywords: Chromium complexes; Pyrrolide-diimine ligands; Polymerization; Ethylene; Homogeneous catalysis; X-ray diffraction.The design of new ligand frameworks for transition metal catalyzed olefin polymerization is a topic of current interest in organometallic chemistry. The investigation of new ligands has been driven by the desire to produce well-defined catalysts that have high polymerization activity and generate polymers with new and useful properties. Recent innovations in the area of ligand design include the bis(imino)pyridines 1 , α-diimines 2 and phenolate imines 3 . These ligands have seen extensive use mainly for late transition metal (i.e., Fe, Co, Ni, Pd) catalyzed olefin polymerization.Other ligand designs that are of current interest are the pyrrolide-imine 4 and pyrrolide-diimine 5 ligands. Pyrrolide-imines and in particular pyrrolide-

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