Bis(diphosphino)methanide and hydride derivatives of Ir4(CO)12

Abstract

The reaction of [Ir₄(CO)₁₀(μ-(Ph₂P)₂CH₂)] with dried KOH forms [Ir₄(CO)₁₀(μ-(Ph₂P)₂CH)]⁻ which subsequently converts into [Ir₄(CO)₉(μ₃-(Ph₂P)₂CH)]⁻, a rare example of an Ir cluster with an Ir–C bond (average 2.274(8) Å). The same reaction with the weaker base 1,8-diazobicyclo[5.4.0]undec-7-ene or with K₂CO₃ in wet CH₂Cl₂ under CO affords the anion [HIr₄(CO)₉(μ-(Ph₂P)₂CH₂)]⁻, a hydride-cluster with an unusually long Ir–H distance (2.08(6) Å at 90 K). Intramolecular CO scrambling is observed in CD₂Cl₂ solution above 200 K, preserving the terminal–axial position of the hydride ligand.