Investigation of Molecular Iridium Fluorides IrF( n ) (n=1–6): A Combined Matrix‐Isolation and Quantum‐Chemical Study

The photo‐initiated defluorination of iridium hexafluoride (IrF(6)) was investigated in neon and argon matrices at 6 K, and their photoproducts are characterized by IR and UV‐vis spectroscopies as well as quantum‐chemical calculations. The primary photoproducts obtained after irradiation with λ=365 nm are iridium pentafluoride (IrF(5)) and iridium trifluoride (IrF(3)), while longer irradiation of the same matrix with λ=278 nm produced iridium tetrafluoride (IrF(4)) and iridium difluoride (IrF(2)) by Ir−F bond cleavage or F(2) elimination. In addition, IrF(5) can be reversed to IrF(6) by adding a F atom when exposed to blue‐light (λ=470 nm) irradiation. Laser irradiation (λ=266 nm) of IrF(4) also generated IrF(6), IrF(5), IrF(3) and IrF(2). Alternatively, molecular binary iridium fluorides IrF( n ) (n=1–6) were produced by co‐deposition of laser‐ablated iridium atoms with elemental fluorine in excess neon and argon matrices under cryogenic conditions. Computational studies up to scalar relativistic CCSD(T)/triple‐ζ level and two‐component quasirelativistic DFT computations including spin‐orbit coupling effects supported the formation of these products and provided detailed insights into their molecular structures by their characteristic Ir−F stretching bands. Compared to the Jahn‐Teller effect, the influence of spin‐orbit coupling dominates in IrF(5), leading to a triplet ground state with C (4v) symmetry, which was spectroscopically detected in solid argon and neon matrices.