Ferrocenyl-based phosphine ligands [Fe{1-PPh2(spacer)-2-NMe2CH2C5H3} (C5H5)] (spacer =1,4-phenylene (rac-1), 1,3-phenylene (rac-2), 4,4'-biphenylene (rac-3), 2,5-thienylene (rac-4)) were applied in the rhodium(I)-catalyzed hydroformylation of various olefins (styrene, allylbenzene and 1-hexene) with higher chemo- and regioselectivity than a rhodium(I) catalyst precursor alone. The different sigma-donor properties of rac-1-4 were elucidated by P-31{H-I} NMR spectroscopy of the corresponding selenides. (C) 2013 Elsevier B.V. All rights reserved.