Mechanism and equilibrium constants of the reaction between carbon monoxide and triphenyl-phosphine-, -arsine-, and -stibine-dicarbonyl-(1–2-η:3–4-η-1,4-diphenyl-1-azabuta-1,3-diene)iron

Abstract

Equilibrium and rate data have been measured for the ligand-substitution reaction [Fe(η⁴-C₆H₅CHCHCHNC₆H₅)(CO)₂L]+ CO ⇌[Fe(η⁴-C₆H₅CHCHCHNC₆H₅)(CO)₃]+ L where L = PPh₃, AsPh₃, or SbPh₃. The reaction proceeds via a dissociative equilibrium of the η⁴ complexes to σ unsaturated complexes. Variations of the equilibrium and rate constants appear to be mainly associated with the basicity of the ligands.