Iridium(III) Complex Containing a Unique Bifurcated Hydrogen Bond Interaction Involving Ir−H···H(N)···F−B atoms. Crystal and Molecular Structure of [IrH(η¹-SC₅H₄NH)(η²-SC₅H₄N)(PPh₃)₂](BF₄)·0.5C₆H₆

A synthetic route to a new iridium(III) complex containing a novel proton hydride bonding interaction has been established. fac-IrH₃(PPh₃)₃ reacts with 2-mercaptopyridine HSpy (Spy = 2-SC₅H₄N) to give the known dihydride Ir(H)₂(η²-Spy)(PPh₃)₂ 8. Ir(H)₂(η²-Spy)(PPh₃)₂ reacts with HSpy^.HBF₄ to give [IrH(η¹-SC₅H₄NH)(η²-SC₅H₄N)(PPh₃)₂](BF₄) 9 which possesses a unique bifurcated hydrogen bonding interaction involving Ir−H···H(N)···F−B atoms with the distances of 2.0(1) Å for the H···H unit and of 2.0(1) Å for the F···H unit in the crystalline state. In solution the N−H···H−Ir interaction is maintained according to ¹H T₁(min) and nOe measurements. Isotope shifts in the chemical shifts of the hydride and one phosphorus of 9 have been observed in ¹H and ³¹P{¹H} NMR spectra of [IrH(η¹-SC₅H₄ND)(η²-SC₅H₄N)(PPh₃)₂](BF₄), 9-d₁, prepared by the reaction of 9 with MeOD or CF₃CO₂D. The crystal and molecular structure of [IrH(η¹-SC₅H₄NH)(η²-SC₅H₄N)(PPh₃)₂](BF₄)·0.5C₆H₆ 9 has been solved by X-ray analysis:  monoclinic space group P2₁/c with a = 17.723(3) Å, b = 10.408(1) Å, c = 26.073(4) Å, β = 108.08(1)°, V = 4572.0(11) ų, and Z = 4. The known complex fac-IrH₃(PPh₃)₃, 7, is made by a new and improved method by reacting mer-IrHCl₂(PPh₃)₃ with NaOEt and H₂(g). VT-¹H NMR spectra (+90 to −80 °C) of the hydrides of 7 reveal that the J_AA and J_AX couplings change in the AA‘A‘‘XX‘X‘‘ pattern (A = ¹H, X = ³¹P) but that the complex is not fluxional. The T₁(min) value of 0.144 s for the hydrides of 7 at −60 °C (300 MHz) indicates that the shortest H-H distances are about 1.8 Å.