Synthesis of a Novel Organoiridium(I) Fluoro Complex

Abstract

Cyclooctadienefluorotriphenylphosphaneiridium(I) [IrF(C8H12)(PPh3)] (3) was prepared and its structure determined by single crystal X‐ray diffraction analysis. Complex 3 crystallises in the monoclinic space group P21/n. The lattice parameters are a = 931.9(3) pm, b = 1629.4(7) pm, c = 1592.9(7) pm, α = γ = 90°, β = 92.85(3)°. Number of molecules per unit cell is 4. The square planar iridium complex 3 exhibits an Ir−F bond length of 201.3(5) pm. 3 was obtained in Teflon tubes, whereas the use of glass vessels led to cyclooctadiene‐bis(triphenylphosphane)iridium(I)‐pentafluorosilicate(IV) ([Ir(C8H12)(PPh3)2][SiF5]) (4). The composition of 4 was confirmed by single crystal X‐ray diffraction analysis. 4 crystallises in the monoclinic space group P21/c. The lattice parameters are a = 1157.4(9) pm, b = 1864.4(9) pm, c = 1922.5(17) pm, α = γ = 90°, β = 96.16(7)°. The number of molecules per unit cell is 4. The square‐planar coordinated iridium cation [Ir(C8H12)(PPh3)2]+ is separated from the trigonal bipyramidal [SiF5]− anion by 461.1 pm (shortest Ir···F distance) and thus it is assumed that no interactions occur between the fluorine and iridium atoms. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Routes to unique palladium A-frame complexes with a bridging fluoro-ligand

“…resonance at d 1.9 is covered by the signals of the cyclohexyl group. A quartet (J FH = 5 Hz) with 29 Si satellites (J SiF = 216 Hz) at d −111 ppm in the 19 F NMR spectrum and a quintet at d 0.01 ppm (J HF = 5.0 Hz) in the 1 H NMR spectrum can be assigned to the SiMeF 4 − anion. 32 The NMR data of 2b suggest a similar cationic A-frame structure as it has been found for 2a.…”

“…33 The presence of SiMeF 4 − evidently arises from HF or fluoride attack at the glass tubes. 20,29,34 Sources of the fluoride anions can be fluoro complexes such as [Pd(F)(Me)(Cy 2 PCH 2 PCy 2 )] (I), [{(Pd(F)(Me)} 2 {l-j 2 (P,P)Cy 2 PCH 2 PCy 2 } 2 ] (II) or [(PdMe) 2 -{l-j 2 (P,P)Cy 2 PCH 2 PCy 2 } 2 (l-F)]F (III). Especially an intermediate such as III, which exhibits an outer-sphere anion as a source for a "naked fluoride" seems to be precedented for the formation of an SiMeF 4 − anion.…”

Stabilisation of iridium(iii) fluoride complexes with NHCs

“…Indeed, the development of more reliable synthetic procedures for the synthesis of late transition metal fluoride coordination and organometallic complexes over the past 10-15 years has led to considerable growth in the total number of examples, in the variation in ligand donor sets and in the appreciation of the criteria for M-F bond stabilisation. [1][2][3][4][5][6][7][8] Throughout most of these studies, phosphine, N-donor or s-aryl ligands have routinely been included in the first coordination sphere to aid product stabilisation and characterisation. In contrast, although the coordination chemistry of N-heterocyclic carbenes (NHCs) has been extensively investigated, 9 reports of late transition metal-fluoride-NHC complexes had been restricted to only monofluorides [AuF(NHC)], 10 [RuFH(CO) 2 (NHC) 2 ], 11 [RuFH(CO)(NHC)(PPh 3 ) 2 ] 12 and [NiF(Ar F )(NHC) 2 ], 13,14 until our recent report of the first difluoride complexes [RuF 2 (CO) 2 (NHC) 2 ].…”

15 Noble metals

“…188 [IrF(cod)(PPh 3 )] was prepared by reaction of HF with [{Ir(m-OH)(cod)} 2 ]. 189 Imidazolium salts have been found to bind abnormally via C5 to Ir(I) and Ir(III) to give air-stable monodentate N-heterocyclic carbene complexes; this mode of ligand binding was verified by X-ray crystallography in both cases. In the case of Ir(I), it is necessary to block the C2 and C4 positions to form a stable sterically protected C5-bound complex.…”