Seven novel imidazole and thiazole derivatives of diphos-type ligands are presented. They are of the general structure R2P(CH2)(2)PR2, where R is imidazol-2-yl (1), 1-methylimidazol-2-yl (2), 1-methyl-benzimidazol-2-yl (3), 1-methylimidazol-5-yl (4), 2-isopropylimidazol-4(5)-yl (5), thiazol-2-yl (6), benzothiazol-2-yl (7), thiazol-4-yl (8) or thiazol-5-yl (9). Syntheses involved direct metallation or halogenmetal exchange reactions. Their solubility, especially in aqueous solution, is strongly dependent on the nature of the substituents as is their partition coefficient log D. The crystal structures of compounds 2, 3, 7a and 9 as well as the structure of the rhodium complex (2)(2) , Corinna Wetzel [a] , Melanie Bongartz [a] , Anna-Louisa Noffke [a] and Bernhard Spingler