Ruthenium nitrosyl complexes [RuCl3(NO)(P–N)] bearing an oxazoline-derived P–N ligand (PHOX)

This work presents two complexes with general formula [RuCl3(NO)(PHOX)] (PHOX = 2-[2-(diphenylphosphino)phenyl]-4,4-dimethyl-2-oxazoline). Reaction of the PHOX ligand with [RuCl3(H2O)2(NO)] in refluxing methanol afforded fac-[RuCl3(NO)(PHOX)] (1), whereas exposure of a dichloromethane solution of complex 1 to ambient light gave mer,trans-[RuCl3(NO)(PHOX)] (2). On the other hand, reflux of complex 2 in methanol for 3 h resulted in thermal isomerization, to furnish complex 1. 1H and 31P NMR, elemental analysis, vibrational spectroscopy, UV–Vis, cyclic voltammetry, and X-ray diffractometry (for complex 2) aided characterization of the complexes. This work also compares the chemical properties of complexes 1 and 2 with the properties of similar complexes bearing PMA ([o-(N,N-dimethylamino)phenyl]diphenylphosphine, DPPE (1,2-bis(diphenylphosphino)ethane), and DPPP (1,3-bis(diphenylphosphino)propane); it also offers some insight into photo- and thermal isomerization mechanisms.