Coordination study of ruthenium(II) complexes containing a mixed donor (P–N) ligand

A series of ruthenium(II) complexes containing an o-(diphenylphosphino)aniline (P–N) ligand have been prepared to elucidate the geometric coordination isomers and substitution reactions. Thus, [(P–N)RuCl2(CO)2] (1), [(P–N)RuCl2(dmso)2] (2) and [(P–N)RuCl2(PPh3)] (3) were synthesized by the reactions of various Ru(II) precursors with P–N. Treatment of 2 with CH3CN yielded the substitution product [(P–N)RuCl2(dmso)(CH3CN)] (4). The rate of the dmso ligand self-exchange of 2 was investigated, and ΔG≠ was estimated to be 23.7 kcal/mol, whereas ΔG≠ for the CH3CN ligand self-exchange of 4 was 25 kcal/mol. Replacement of CO in 1 with dmso directly yielded [(P–N)RuCl2(dmso)(CO)] (8). Of course, complex 8 could also be prepared by substitutions of 2 and 4 with CO, but through various intermediates. Furthermore, the substitution reaction of 3 with CO and dmso led to the formation of 8, and complexes 2 and 3 were inter-convertible. The stereochemistry of all the Ru(II) complexes has been established by elemental, spectroscopic and X-ray crystal structural analyses.

Graphical abstractHerein we have synthesized and characterized a series of ruthenium(II) complexes based on a mixed chelating (diphenylphosphino)aniline (P–N) ligand. Ligand substitution reactions among these complexes have been investigated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis and characterization of a series of [(P–N)RuLnClm] complexes. ► Substitution reactions among these ruthenium(II) complexes have been investigated. ► Kinetic studies provided the insight of the substitution pathway.