New Sc(III) chloro-complexes [ScCl2(NNCp)(THF)] (1), [ScCl2(NNO)(THF)] (2) and [ScCl2(NNHO)(THF)] (3) {NNCp = 6-cyclopentadienylmethyl-pyridin-2-ylmethylene)-(2,6-diisopropyl-phenyl) -amine; NNO=2-tert-butyl-6-((quinolin-8-ylimino)methyl)phenolate); NNHO = 2-tert-butyl-6-((quinolin-8-ylamino)methyl)phenolate) have been synthesized and characterized by NMR and mass spectrometry. The comparative results of the catalytic behavior of these scandium complexes towards ethylene and butadiene polymerization are reported and explained on the basis of the electronic and steric properties of the ancillary ligands. (c) 2008 Elsevier B.V. All rights reserved.