The synthesis of bidentate aminophosphine ligands (PNquin) based on 8-hydroxyquinoline is described. These ligands react with cis-Fe(CO)(4)Br-2 to give selectively octahedral complexes of the type cis, cis-Fe(PNquin)(CO)Br-2(2). There is only one isomer formed where the two CO and the two bromide ligands adopt a cis configuration. The reaction of [RuCp(CH3CN)(3)]PF6 with PNquin ligands affords the halfsandwich complexes [RuCp(PNquin)(CH3CN)]PF6 in high isolated yields. Likewise, treatment of [Ru(eta(6)-p-cymene)(mu-Cl) Cl](2) with PNquin in the presence of AgCF3SO3 affords halfsandwich complexes of the type [Ru(eta(6)-pcymene)(PNquin) Cl]CF3SO3. All ligands and complexes are characterized by NMR and IR spectroscopy. The X-ray structure of representative compounds is reported. In addition, the relative stability of isomeric structures and conformers of Fe(PNquin-Ph)(CO)(2)Br-2 is studied by means of DFT calculations. (c) 2010 Elsevier B. V. All rights reserved.