Synthesis

4.2.1 Preparation of 4-(tridecafluorohexyl)bromobenzene1

This was prepared following the literature method and further advice provided by Dr D. Adams from University of Leicester.1

1-bromo-4-iodobenzene (25.0 g, 88.34 mmol), copper bronze (12.36 g, 193.13 mmol), 2,2’-bipyridine (0.98 g, 6.36 mmol), DMSO (200 cm3) and fluorobenzene (150 cm3) were mixed under nitrogen and heated to 70 oC. To this was added a solution of perfluoro-n-hexyliodide (39.42 g, 88.4 mmol) in perfluorobenzene (50 cm3) dropwise over the course of 7 hours. By careful monitoring the temperature of the reaction solution was maintained at 70oC. The mixture was then left stirring at 70 o

C for 120 hours after which the mixture was cooled overnight.

The reaction mixture was added to a large conical flask containing water (200 cm3) and diethyl ether (500 cm3). This solution was filtered to remove the precipitate, which was washed with diethyl ether (2x 50 cm3). The organic layer was separated and washed with water (5x 250 cm3); dried over magnesium sulfate; filtered and the solvent removed using a rotary evaporator. This resulted in a brown oil. Leaving this overnight, crystals (1-bromo-4-iodobenzene) formed in the oil. The oil was filtered and then heated in a kugelröhr at 65oC to remove unreacted 1-bromo-4-iodobenzene, the oven temperature was then raised to 100oC to distil the 4- (tridecafluorohexyl)bromobenzene and 1,4-bis (tridecafluorohexyl)bromobenzene as a

clear oil. This clear oil was distilled using microfine distillation apparatus to give 4- (tridecafluoro)bromobenzene as a colourless oil (b.p. 89-92 oC at 10 mbar) (17.8 g, 42.3 %) 1H (300 MHz, CDCl3) 7.5 (2H, d, 3JHH=8.2 Hz), 7.3 (2H, d, 3JHH= 8.2 Hz).

Literature values1H(250 MHz, CDCl3) 7.90 (2H, d,3JHH=8.5 Hz), 7.70 (2H, d,3JHH= 8.5 Hz).

4.2.2 Synthesis of Tris(4-tridecafluorohexylphenyl)phosphine

4-(Tridecafluorohexyl)bromobenzene (24.0 g, 50.53 mmol) was degassed under high vacuum before backfilling the flame-dried Schlenk tube with argon and adding dry diethyl ether (300 cm3). This solution was stirred and cooled to –78 oC with a dry ice/acetone bath. A solution of 1.6 M n-BuLi in hexane ( 31.5 cm3, 50.4 mmol) in dry diethyl ether (30 cm3) was added to the main flask dropwise over 60 minutes, ensuring the internal temperature never rose above –75oC. The mixture was stirred for 5 hours at –78 oC, at which point the dropping funnel was rinsed with dry diethyl ether (10 cm3) then charged with dry diethyl ether (30 cm3) and phosphorus trichloride (2.29 g, 16.72 mmol). This solution was added dropwise over 60 minutes with the temperature maintained below –75 oC. The reaction mixture was then allowed to warm to room temperature overnight. Ammonium hydroxide solution (10 % in water, 100 cm3) was added to the reaction mixture and stirred for 20 minutes. The organic solution was then separated and transferred to a flame-dried Schlenk tube containing MgSO4 via cannula. This mixture was stirred for a further 20 minutes before removing the solution to a flame-dried Schlenk tube using a filter stick. The solvent was removed in vacuo, resulting in a yellow oil, which solidified when left overnight. The resulting solid was dissolved in dry, degassed DCM, the solution transferred to a Schlenk tube containing silica and the solvent removed in vacuo –

adsorbing the impure ligand onto the surface of the silica. This silica was transferred under argon to a column already containing some pure silica, with care being taken to ensure the yellow silica remained on the top of the column. The product was eluted with petrol (b.p. 40-60oC) and the solvent was removedin vacuo resulting in a white powder. The product/petrol solution was passed over a second column of pure silica, if it retained the yellow impurity. The yield for this step is very low ~26 %. 31P NMR: (300 MHz, CDCl3)δ: -5.2 Literature31P NMR (101Hz,CDCl3) –6.3.

4.2.3 Reduction of Tris(4-tridecafluorohexylphenyl)phosphine oxide3

Tris(4-tridecafluorohexylphenyl)phosphine oxide (2.5 g, 2.1 mmol) (obtained through oxidation of tris(4-tridecafluorohexylphenyl)phosphine during synthesis), triethylamine (6.3 cm3, 45.2 mmol), trichlorosilane (3.0 cm3, 29.7 mmol) and toluene (20 cm3) were added to a 100 cm3 flask. Stirring the flask vigorously under an argon atmosphere, the reaction mixture was heated to 120oC for 6 hours. The mixture was cooled to RT and then cooled further with an ice bath. A saturated NaHCO3aqueous solution (1 cm3) was added to the reaction mixture and stirred for 10 minutes. The yellow solution was filtered through a silica column and washed with hexane. The solvent was removedin vacuo and a clear colourless oil was obtained this was left in the glove box to solidify to a white powdery solid.

4.2.4 HPNMR solutions

4.2.4.1 Toluene-d

Solutions

P(-4-C6H4C6F13)3 (0.1215 g, 0.1 mmol) was weighed into a Schlenk tube containing [Rh(acac)(CO)2] ( 0.0052 g, 0.02 mmol) in the glove box. To this was added degassed toluene-d8 (2 cm3) and the solution was stirred until all solid had dissolved and was then transferred to the degassed HPNMR cell.

After preforming the catalyst at 70 oC under 20 bar CO/H2, the 1-octene (0.5 cm3) was added under a stream of argon and the cell re-pressurised. All triphenylphosphine solutions were prepared in this way, but both the Rh precursor and triphenylphosphine could be weighed out in air.

4.2.4.2 Hexane-d

Solutions

P(-4-C6H4C6F13)3 (0.1215 g, 0.1 mmol) was weighed into a Schlenk tube containing [Rh(acac)(CO)2] ( 0.0052 g, 0.02 mmol) in the glove box. This was then dissolved in perfluoro(1,3-dimethylcyclohexane) (PFDMC, 1.5 cm3). Hexane-d14(0.5 cm3) was added to the solution, which was stirred under argon until all solid had dissolved. Both solvents had been previously freeze-pump-thawed.

4.2.5 HPIR Solutions

Triphenylphosphine and [Rh(acac)(CO)2] were weighed directly in to the HPIR cell which was then sealed and degassed by purging with N2 gas (direct from cylinder) for 30 minutes. Then dry degassed hexane (30 cm3) was added by syringe through the injection port under a stream of nitrogen.

Solutions of tris(4-tridecafluorohexylphenyl)phosphine were made up by weighing the [Rh(acac)(CO)2] into a Schlenk tube before taking this into the glove box and weighing out the P(C6H4C6F13)3into that Schlenk tube and finally dissolving in degassed hexane. The mixture was stirred and some heating (hot air gun) was often required to ensure total dissolution of the solids. The solution was then injected into the previously degassed HPIR cell under a stream of nitrogen. The cell was sealed and placed into the spectrometer. The spectra were collected as detailed in section