Hydrogen and oxygen activation by an iridium precursor containing the 4,5-bis(diphenylthiophosphinoyl)-1,2,3-triazolate ligand

Abstract

The novel mononuclear complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(coe)₂] was prepared starting from the dimer [Ir(coe)₂(μ-Cl)]₂ (coe = cyclooctene) and potassium 4,5-bis(diphenylthiophosphinoyl)-1,2,3-triazolate, K[4,5-(P(S)Ph₂)₂Tz]. Reaction of [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(coe)₂] with two equivalents of PPh₃ led to complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(PPh₃)₂]; which, upon exposure to atmospheric air at room temperature, fixed molecular oxygen to produce complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(PPh₃)₂O₂]. Molecular hydrogen also added oxidatively to complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(PPh₃)₂] to form the Ir(III) dihydride complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(PPh₃)₂(H)₂]. Carbon–hydrogen bond activation was effected when complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(coe)₂] was made to react with triphenylphosphite to give the ortho-metallated complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(P(OC₆H₄)(OPh)₂)(P(P(OPh)₃)(H)]. The new compounds were characterized by spectroscopic methods and, excepting for [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(PPh₃)₂], by single crystal X-ray analysis. Oxygen and hydrogen activation by the diphosphane complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(PPh₃)₂] compared with the inertness of the diolefin complex [Ir(κ²-S,N-(4,5-(P(S)Ph₂)₂Tz))(coe)₂] to such processes was assessed by means of a DFT-QTAIM analysis.