Kinetic and mechanistic examination of NBu4[IrH2(CO)2I2] and NBu4[RhH2(CO)2I2] via para-hydrogen enhanced NMR spectroscopy

Abstract

para-Hydrogen enhanced NMR signals are used to show that NBu₄[M(CO)₂I₂] (M = Rh, Ir) add hydrogen to form NBu₄- {all-cis-[M(H)₂(CO)₂I₂]} which for M = Ir undergoes H₂ elimination in a step where ΔH‡ 106 ± 10 kJ mol^–1 and ΔS‡± 6 J K^–1 mol^–1 while showing a rich substitution chemistry with PPh₃ that leads to both charged and neutral products via square pyramidal Ir(H)₂(CO)₂I.