Syntheses and Molecular Structure of Some Rh and Ru Complexes with the Chelating Diphenyl (2-Pyridyl)phosphine Ligand

The rhodium(III) complex mer,cis-[RhCl₃(PPh₂py-P,N)(PPh₂py-P)] (1) (PPh₂py = diphenyl (2-pyridyl)phosphine) has been prepared from RhCl₃·3H₂O and PPh₂py and converted to the trans,cis-[RhCl₂(PPh₂py-P,N)₂]PF₆ (2) in acetone solution by treatment with Ag⁺ and PF₆^-. Ruthenium(III) and ruthenium(II) compounds with PPh₂py, mer,cis-[RuCl₃(PPh₂py-P,N)(PPh₂py-P)] (3) and mer-[RuCl(PPh₂py-P,N)₂(PPh₂py-P)]Cl (5) have been obtained from DMSO precursor complexes. In a chloroform solution, complex (5) isomerizes to fac-[RuCl(PPh₂py-P,N)₂(PPh₂py-P)]Cl (fac-5). All compounds have been characterized by MS, UV−vis, IR, and ¹H and ³¹P{¹H} NMR spectroscopy, and the Ru(III) compound has been characterized by EPR spectroscopy as well. The crystal structures of 1, 2, 3, and fac-5 have been determined. In all compounds under investigation, at least one pyridylphosphine acts as a chelate ligand. The ³¹P chemical shifts for chelating PPh₂py-P,N depend on the Ru−P bond lengths.