Coordinatively labile 18-electron arene ruthenium iminophosphonamide complexes
Résumé
The thermodynamics of chloride dissociation from the 18e arene ruthenium iminophosphonamides [(η6‐arene)RuCl{(R′N)2PR2}] (1 a–d) [previously known with arene=C6Me6, R=Ph, R′=p‐Tol (a); R=Et, R′=p‐Tol (b); R=Ph, R′=Me (c); and new with arene=p‐cymene, R=Ph, R′=p‐Tol (d)] was assessed in both polar and apolar solvents by variable‐temperature UV/Vis, NMR, and 2D EXSY 1H NMR methods, which highlighted the influence of the NPN ligand on the equilibrium parameters. The dissociation enthalpy ΔHd decreases with increasing electron‐donating ability of the N‐ and P‐substituents (1 a, 1 d>1 b>1 c) and solvent polarity, and this results in exothermic spontaneous dissociation of 1 c in polar solvents. The coordination of neutral ligands (MeCN, pyridine, CO) to the corresponding 16e complexes [(η6‐arene)Ru{(R′N)2PR2}]+PF6− (2 a–d) is reversible; the stability of the 2⋅L adducts depends on the π‐accepting ability of L. Carbonylation of 2 a and 2 d resulted in rare examples of cationic arene ruthenium carbonyl complexes (3 a, 3 d), while the monocarbonyl adduct derived from 2 c reacts further with a second equivalent of CO with conversion to carbonyl‐carbamoyl complex 3 c, in which one CO molecule is inserted into the Ru−N bond. The new complexes 1 d, 2 d, 3 a, 3 c, and 3 d were isolated and structurally characterized.
Domaines
Chimie de coordination
Origine : Fichiers produits par l'(les) auteur(s)