Synthesis and characterisation of some iridium-carbonyl-fluoride complexes. Crystal structures of [IrF(CO){P(C6H4-2-CH3)3}2] and [IrF2(COD)py2][BF4]

Abstract

Two routes to iridium(III) fluorocomplexes are described. The direct reaction of tetrairidium dodecacarbonyl with elemental fluorine in aHF offers a clean, convenient, large scale route to [IrF(3)(CO)(3)]; addition of phosphines to [IrF(3)(CO)(3)] in THF affords mer-[IrF(3)(CO)L(2)] or [IrF(CO)L(2)]. Alternatively, cationic [IrF(2)(COD)L(2)](+) and [IrF(2)(CO)(2)L(2)](+) (L = phosphine, pyridine; L(2) = alpha-diimine) are accessible via the oxidation of the iridium(I) precursors with xenon difluoride.

Synthesis and Reactivity of Iridium(I) Fluorido Complexes: Oxidative Addition of SF4 at trans‐[Ir(F)(CO)(PEt3)2]

“…The metal carbon distance in 9 is longer than in trans ‐[Ir(Cl)(CO)(PCy 3 ) 2 ] ( 4 ) [Ir–C: 1.788(10) Å], which is also observed when comparing the analogous rhodium complexes. [5f], The Ir–F distances [1.965(5) Å for 9 , 1.9846(19) Å for 10 ] are well comparable to these in other iridium(I) fluorido complexes as well as to the one observed in trans ‐[Ir(F)(CO)(P{C 6 H 4 ‐2‐CH 3 ) 3 } 2 ] …”

“…[15a], [24b] Additionally the triplet couplings of 34 Hz and 29 Hz suggest that both metal fluorides have two phosphine ligands in a cis position. [15a], [24d] The 13 C labeled isotopologue 11' doesn't show further splitting of the signals for the sulfur bound fluorine atoms, but an additional doublet splitting of 77 Hz and 5 Hz is observed for the resonances of the metal fluorides at δ = –314.6 and –366.6 ppm, respectively. [5f], , [24d], [24e], [24f] A larger 2 J F,C coupling of the carbonyl ligand to a fluoride in the trans position than to a fluoride in the cis position has been observed before, and this allows for an assignment of both resonances.…”

“…[27a], The CO stretching mode at 2064 cm –1 confirms the presence of an iridium compound in oxidation state +III. [15a], [24c], …”

Synthesis, Structure and Reactivity of Iridium Hydrido Fluorido Complexes

“…This indicates a hindered rotation aboutthe Ir–C bond 13,16. A broad singlet at δ = –267.4 ppm verifies the presence of the fluorido ligand 9h,12a,17. The signal remains broad at low temperature (223 K).…”

“…Four multiplets in the 19 F{ 1 H} NMR spectrum indicate a hindered rotation of the tetrafluoropyridyl ligand about the Ir–C bond 13,16. A broad singlet can be found at δ = –444.3 ppm for the metal‐bound fluorine atom 5a,9h,17. The 1 H NMR spectrum of 4a shows a multiplet for the hydrido ligand at δ = –5.90 ppm.…”