Synthesis and characterization of iron and ruthenium complexes bearing P–N ligands based on 8-hydroxyquinoline

The synthesis of bidentate aminophosphine ligands (PNquin) based on 8-hydroxyquinoline is described. These ligands react with cis-Fe(CO)4Br2 to give selectively octahedral complexes of the type cis,cis-Fe(PNquin)(CO)2Br2. 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(η6-p-cymene)(μ-Cl)Cl]2 with PNquin in the presence of AgCF3SO3 affords halfsandwich complexes of the type [Ru(η6-p-cymene)(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)2Br2 is studied by means of DFT calculations.