fac-mer Isomerization processes of octahedral ruthenium(II) complexes [RuCl 2 (dppm)(FcPN)] containing the chelate ligands (4S)-2-[(S p )-2-(diphenylphosphino)ferrocenyl]-4-(methylethyl)oxazoline (FcPN) and bis(diphenylphosphino)methane (dppm) are described. A five-coordinate intermediate [RuCl(dppm)(FcPN)][Cl] involved in this isomerization was isolated as its hexafluorophosphate salt. The alkynyl complex mer-[RuCl(C≡CC 6 H 4 CH 3 -4)(dppm)(FcPN)] (4) has been prepared by reaction of fac-[RuCl 2 (dppm)(FcPN)] with LiC≡CC 6 H 4 CH 3 -4. Azide complexes fac-[Ru(N 3 ) 2 (PR 3 ) x (FcPN)] (R=Ph, x=1 (5), R=Me, x=2 (6)) have also been prepared by treatment with NaN 3 of [RuCl 2 (PPh 3 )(FcPN)] and fac-[RuCl 2 (PMe 3 ) 2 (FcPN)], respectively. Bubbling CO through a dichloromethane solution of the five-coordinate complex [RuCl 2 (PPh 3 )(FcPN)] leads to [RuCl 2 (CO)(PPh 3 )(FcPN)] (7) which undergoes phosphine exchange with pyridine to yield cis-[RuCl 2 (CO)(py)(FcPN)] (8). Reaction of 7 with dppm in the presence of NaPF 6 gives the cationic complex [RuCl(CO)(dppm)(FcPN)][PF 6 ] (9). X-ray structures of the complexes mer-trans-[RuCl 2 (dppm)(FcPN)] (1) and cis-[RuCl 2 (CO)(py)(FcPN)] (8) are also reported.